Inspirations: The Lie of the Land

Not a great deal to say about this one, as we've covered a lot of the background already.

The final part of the Monks trilogy originated with Toby Whithouse's idea for a story based on the sort of totalitarian society seen in George Orwell's 1984. The writer then had to make this act as a sequel, and conclusion, to the previous episodes.

Steven Moffat liked the idea of an invasion that had already taken place - and the Doctor appearing to be collaborating with the invaders. As the darkest iteration of the Time Lord to date, viewers might actually believe that he really had gone over to them.

His role appears to be inspired by Nazi propagandist "Lord Haw-Haw" - William Joyce - whose "Germany Calling..." broadcasts to Britain during WWII were designed to sap morale. He was the inspiration for the villain in Sherlock Holmes and the Voice of Terror (1942). Joyce was hanged for treason in January 1946.

The Doctor appearing to be undergoing a regeneration, but not actually going through with it, had been seen in the cliffhanger to The Stolen Earth, and the Eleventh Doctor had undergone a non-regeneration in The Impossible Astronaut. In the former case, he did use up a life and had to redirect the regeneration energy into a compatible organic receptacle (his hand), whilst in the case of the latter incident it was only a robot copy of the Doctor.

The main element taken from Orwell's novel - written in 1948 and published the following year - was the idea of the Ministry of Truth, which was basically a propaganda machine which presented history as the rulers wished it to be seen, not as had actually taken place.

"Fake news" was a big thing in the media at the time of writing this episode, coming especially from the first Trump presidential campaign where anything negative was dismissed as made-up. It continues to this day.

Whithouse was notified that his episode would be the one where the Vault would finally be opened, and so Missy would feature once again.

It was originally intended that her prison would be a spartan affair. It would be she who would give the Doctor the solution to defeating the Monks, having had previous dealings with them.

The episode opened with a collage of fake history, as presented by the Monks. They would appear in artworks, photographs and newsreel footage, being present at a number of momentous world events as well as appearing in some of the Doctor's own adventures, dealing with Daleks, Cybermen and Weeping Angels.

Moffat had already used this technique to plant the Silents throughout history. Woody Allen had built a whole movie around the idea - 1983's Zelig.

Instead of Orwell's Thought Police, Whithouse introduced the Memory Police - who arrested people who harboured memories of real history.

Having events move on by 6 months from the previous episode, with the Earth already subjugated, reminds us of The Last of the Time Lords. In this, the Master had built a gigantic statue of himself.

A statue which actually acted as a psychic transmitter / receiver was an idea which featured in Douglas Adams' original idea for what later became The Pirate Planet. Then, it was one built by the Time Lords to absorb negative emotions and so pacify a planet's population. A Time Lord sent to dismantle it was caught up in the works and himself absorbed all the negativity, to become the story's villain.

Ordinarily, the Doctor prevents invasions - but having him have to deal with a planet that has already been taken over goes right back to The Dalek Invasion of Earth.

The Doctor's room on the prison ship was described as looking like the one astronaut Bowman finds himself in as an old man at the end of 2001: A Space Odyssey - a stark, brightly lit white space.

The Monk generating thought waves at the heart of the London Pyramid - described in the script as their Cathedral - was to be seen sitting in the pose of Rodin's The Thinker statue (1880).

Next time: Zulu, but with Ice Warriors...

Inspirations: The Pyramid at the End of the World

 

We explained the general inspiration for this trilogy of episodes last time. Writer Peter Harness's idea had involved "Kung-fu Monks" whilst Steven Moffat had actually considered destroying the Earth - but as separate stories. The showrunner then decided to merge these, plus Toby Whithouse's 1984 Orwellian society drama, into a single storyline.

Harness wanted his episode to be a comment on current world affairs, similar to what he had done with his Zygon two-parter the series before, which had dealt with issues of radicalisation amongst young Muslims. The background was Donald Trump's first run for the Presidency of the United States. He felt that what Trump was offering to the American people was simply a short-term fix, one that might prove disastrous in the longer term.

The aliens would therefore appear benign initially, in order to take in their intended victims. This idea had been used before by Bob Baker & Dave Martin in The Claws of Axos - an idealised family group of golden skinned humanoid, bearing gifts, who were actually tentacled monsters, out to destroy all life on Earth. It was also the M.O. of the Nimon in The Horns of Nimon. 

He hit upon the aliens as monks - generally peace-loving, spiritual individuals.

The "Kung-fu" aspect came from the fact that they were initially supposed to have martial arts skills.

They would turn out to be blackmailers from another dimension, who observed probabilities to seek out points in time when a race might be at its most vulnerable, then step in to appear to offer salvation.

Researching potential flash points in recent history, Harness noted an occasion when a Norwegian rocket was launched from the US for scientific purposes, but was mistaken for a missile by the Russians in 1995, and another incident in 1983 when the Russian satellite defence system had erroneously flagged up an attack.

It was going to be revealed that the Monks had tried to intervene before during these events, as well as the Cuban Missile Crisis of 1963, but this information had been supressed by the three major powers.

For his episode, he decided to go with a story he had read about an artificially created soil bacteria named Klebsiella planticola, which broke down plant waste and turned it into ethanol. However, this had only ever been tested in laboratory conditions using sterile soil, and in nature it would prove to be much more powerful - potentially destroying healthy plants.

We are naturally reminded of the insecticide DN6 in Planet of Giants, which appears effective to its creator in the laboratory but will actually destroy all insect life, including that which is essential for agriculture. Harness was actually going to call his soil bacteria DN8, and it was to have been manufactured by Global Chemicals - the company responsible for The Green Death.

This was changed as there is a real company of that name, though one which has never knowingly created a race of giant maggots (as far as we know...).

Hungover lab assistant Douglas was to have had a conversation with Erica about boiled eggs for lunch - a nod to the discussion between scientists Phillips and Goodge in Terror of the Autons.

Harness looked to his Zygon story for other elements. The Doctor would once again be made President of Earth, and the Monks would arrive in the disputed region of Turmezistan. This was where the Zygon rebels had established their base. Here, it is a potential point of conflict between the US, Russia and China.

Whilst the UN features, through the presence of its Secretary General, UNIT does not - despite this being right up their street. (UNIT had become disassociated from the United Nations back in The Sontaran Stratagem, but as an independent multi-national organisation you would have thought they ought to have been involved. They had actually been included in Harness's original storyline, including the return of Kate Stewart. She couldn't appear anyway as Jemma Redgrave had just taken on a regular role in Holby City).

The appearance of the Monks as mummies came from images Harness had seen of mummified corpses in catacombs, which he thought would make for a striking visual image.

Bill's role had to be pivotal. It would be she who would permit the Monks to intervene on Earth - more for saving the Doctor than for the whole world. His blindness - introduced in Oxygen by Jamie Matheison and carried over by Moffat, would lead to him having to be saved.

Bill was originally going to appear to have been vapourised by the Monks on her acceptance of their help, which would form part of the cliffhanger for resolution in the next episode.

Mention is made of the Doomsday Clock. This was created in 1947 by the Manhattan Project scientists to measure the imminent danger of human-made catastrophe. Midnight would signal the end of the world. As of January 2026 it has been set at 85 seconds to midnight - the highest it has ever been. This is due to the on-going risk of nuclear warfare, as well as the mounting concerns about the climate and the rise of Artificial Intelligence.

Next time: The Monks party like it's 1984. The Doctor looks like he's gone over to the dark side, until Bill shoots him...

Inspirations: Extremis

Extremis did not start life as the first episode of a trilogy. Toby Whitehouse was working on a script involving an Orwellian society similar to 1984, whilst Peter Harness had an idea involving Kung-Fu monks.

Steven Moffat himself was pondering something big for the middle of the series - the destruction of the Earth, until he realised how that would impact future storytelling.

Moffat had then agreed to carry on Jamie Mathieson's idea of having the Doctor remain blind after the conclusion of his episode Oxygen.

The showrunner decided to bring these various threads together.

Basically, alien monks would almost bring about the end of the world, but usher in instead a dystopian Orwellian society. The Doctor's disability would - at least initially - prove a handicap to countering this threat.

Bill's role in events would be pivotal in the trilogy's development. It was also planned to make this the time to reveal who was in the Vault.

Moffat needed a starting point which he would write himself, and that's where this episode comes in...

Much of the episode is set in the Vatican's secret library - the Archivum Secretum. Part of the Vatican Library, it contains papal documents including letters to and from international leaders, as well as historic artefacts such as the trial record of Galileo, the Bull excommunicating Martin Luther, and Henry VIII's petition to have his marriage to Catherine of Aragon annulled.

It also contains documents regarded as heretical, and many believe that it holds secret evidence which would actually undermine the Vatican's authority - or even destroy the very foundations of Christianity, deliberately suppressed.

This takes us into Dan Brown territory. He has written a number of potboiler thrillers, some made into movies starring Tom Hanks, which were themselves inspired by supposedly factual books written by - amongst others - the co-creator of the Great Intelligence and the robot Yeti.

A court case cleared Brown of wilfully plagiarising The Holy Blood and the Holy Grail, a 1982 work by Michael Baigent, Richard Leigh and Henry Lincoln, despite The Da Vinci Code (2003) clearly being inspired by its hypothesis - namely that Jesus had a child with Mary Magdalene and eventually founded the Merovingian dynasty. The Vatican allegedly knows all this but suppresses it, but it is knowledge preserved by a secret society known as the Priory of Sion.

Instead of a murder in a museum triggering a story, here we have a bizarre suicide in a library - which turns out to be one of a series of similar deaths. All are people who have read a book - the Veritas. 

The story's title Extremis can mean "at the point of death" (Missy's execution and the "deaths" of the virtual Doctor and companions), or to refer to an extremely difficult situation - something pushed to its furthermost limit.

Another literary inspiration, involving murder in an ecclesiastical library and the suppression of secret knowledge, is Umberto Eco's 1980 novel The Name of the Rose. This has also been adapted for cinema (1986) as well as a 2019 TV mini-series.

Whilst Presidents and Prime Ministers were fair game in drama, Moffat was concerned about the inclusion of the Pope in the episode, not wishing to cause offence, and he actually had the BBC clear this in advance. Whilst scenes involving the fictitious Pope are humorous, he is not himself made a figure of fun. Unlike other figures of authority over the years, the Doctor shows him respect.

The Doctor claims to have known Pope Benedict IX, who was Bishop of Rome in 1045. Benedict - real name Theophylact of Tusculum, reigned three times between 1032 and 1048. One of the "Bad Popes" he was deposed, resigned and sought to enrich himself from the position - even selling the Papacy at one point.

His life was reputedly one of scandal, including murder, rape and sodomy. He may possibly have been the youngest ever Pope, as one record claims he was only 11 or 12 when he ascended the Papal throne, though others claim he was aged 20.

A woman was alleged to have become Pope in the 9th Century, known as Pope Joan. This story only surfaced in the 13th Century and is believed to be pure fiction.

She was only found to be a woman when she gave birth during a procession, and future Popes avoided the spot where this was supposed to have happened. Belief in her existence was such that, until 1600, she had a statue amongst all the other Popes in Siena Cathedral. It was remodelled to make it masculine.

A ritual was created to ensure that no other woman could ever become Pope. During their coronation, an official would physically check their genitalia on a special chair.

One other area Moffat wanted to include in the episode was the notion of reality being an artificial construct. This had featured in several scientific and philosophical theories, but became famous through The Matrix film franchise.

Basically, we are all living in a Virtual Reality simulation, and occasionally there are glitches which reveal this fact.

The VR reveal takes place at CERN - the European Laboratory for Particle Physics. The organisation behind it was founded in 1954 and it was originally based at the University of Copenhagen under Niels Bohr. It later moved to Switzerland. It is best known for the Large Hadron Collider - a circular tunnel 27km in circumference, inaugurated in 2008. Some people at the time believed that it would create a Black Hole and destroy the planet. (Its opening was marked by a BBC radio Torchwood drama).

Moffat's son Joshua had just served a summer internship at CERN prior to studying Physics at university.

The oval-shaped doorways to other simulated locations were based on the video game Portal.

Nardole likens this to the Holodeck in Star Trek: The Next Generation, which was based on an episode of the animated series.

The story ends with a confrontation between the Doctor and one of the Monks in the Oval Office in the White House - a location which had featured prominently in The Impossible Astronaut / Day of the Moon.

The idea that a would-be invader might use a simulation as a precursor to invasion goes back at least as far as the Cold War. It was claimed that fake English villages were built behind the Iron Curtain to train spies.

This crops up in a number of TV dramas, such as Danger Man and The Avengers.

In Doctor Who we had seen it most notably in The Android Invasion, where the Kraals create a mock-up village of Devesham to test out their androids.

Before the Flood, just the season before this one, had been set partly in a fake Russian village in a Scottish valley in the 1980's.

After considering various characters such as Davros for the Vault inhabitant, Moffat had quickly decided on it being Missy. He knew that the mystery could not be sustained for the entire series, so opted to have her revealed at the mid-point. Moffat wanted to examine a new dynamic between her and the Doctor, which would feed into the later stages of the season. Missy is beginning to question her previous lifestyle and is apparently seeking redemption and a change from her evil ways.

The flashback sequences to the Executioners' planet also allowed the audience to see how Nardole came back into the Doctor's life - sent by his wife River Song. He has her journal - first seen in Silence in the Library / Forest of the Dead.

It is said that Time Lords have three brain stems, which confirms Missy's advice that Kate Stewart use two additional snipers in The Magician's Apprentice.

She claims to have known about the Doctor's retirement to Darillium from the Daleks - referencing both The Husbands of River Song and The Witch's Familiar.

Next time: the Monks set up a pyramid scheme, and we learn of the dangers of going to work with a hangover...

Inspirations: Oxygen

In 2005, former CEO of Nestlé Peter Brabeck-Letmathe tried to argue that water was not a human right. It was simply a commodity like anything you might buy in a shop, and had a market value.

By 2013 he had backtracked in his view, following the understandable outcry. 

It's this sort of commercialisation of what most would agree to be a basic human necessity which forms the backdrop to this episode.

We are in deep space, and the essential element here is oxygen. A mining rig on an otherwise lifeless asteroid is owned by a faceless corporation on Earth, and its crew have to pay for their air supply.

There's no safety net. If your stock runs out, you suffocate and die.

The story began life as a request from Steven Moffat to writer Jamie Mathieson for an adventure set in outer space. The showrunner wanted it to highlight just how hostile and deadly space could be. He had been inspired by the recent movie Gravity and the 1995 film Apollo 13.

Mathieson's original idea was of a spaceship graveyard. A group of survivors were being forced to jump from wreck to wreck in search of oxygen and other supplies, hunted all the time by savage crystalline monsters.

They were controlled by a queen who dwelt on a nearby asteroid. She mimicked distress signals to ensnare passing ships. An additional complication was that the survivor group consisted of people from opposing factions in a war. There was also an element of The Thing, in that the monsters could mentally manipulate people, so paranoia was rife amongst the survivors.

The story would have ended with an ethical debate about whether or not they should kill the queen.

It was then decided to ditch the monsters, other than the queen, and simply have space itself the threat, but with the additional danger of zombies - animated human cadavers. These would have some sort of intelligence, however. It was the queen which controlled them. 

The spaceship graveyard was still the setting, and the people encountered by the Doctor and Bill were now simply shipwrecked scavengers.

This time, the episode ended with the Doctor forming a psychic link with the queen to stop it from killing.

Two of the characters were named after family friends of the writer - Darren and his son Ivan, who was a fan of the show. The former became Dahh-Ren, who was originally going to have a multi-eyed spider-like face. Budget restraints reduced this to him simply having blue skin.

As much as Moffat liked the story, he asked Mathieson to pare it down to essentials. He proposed that the zombies be manipulated by their spacesuits. He was worried that they might resemble too closely the skeletons in spacesuits from his own Silence in the Library / Forest of the Dead.

The more zombified look of the cadavers - exposed to the vacuum of space - was retained.

It was Moffat who then suggested that the crew of a mining vessel be forced to purchase their oxygen from the corporation which employed them. This could be withheld if the operation was unprofitable.

An added threat was that the smartsuits could electrocute their owner or anyone they touch.

The suits quite literally become the menace.

"Suits" is slang for business executives and bosses - i.e. the men in suits who run things.

Together Moffat and Mathieson decided on bringing back GUS from the writer's previous story Mummy on the Orient Express, whose origins had been left vague. This would stand for Ganymede Systems.

Mathieson then drew on his own experience of working long hours for bad wages for large corporations.

In the end, the references to GUS would be dropped.

The mining vessel was named Chasm Forge, after the Valley Forge from the 1972 ecological sci-fi movie Silent Running.

Mathieson proposed that the Doctor should be blinded for the second half of the story, after sacrificing his sight to save Bill. He later suggested that the Doctor remain blind at the end of the story - expecting this to be rejected. Moffat decided to incorporate this into the next two scripts.

Nardole's role in Series 10 had only developed late in the day, and he was originally going to be brought into the story after the Doctor and Bill set off without realising he was on the TARDIS.

He didn't feature in the earlier drafts.

At one point the Doctor lies to Nardole about one of the fluid links. He had first used these as an excuse to explore in The Daleks, and they were a feature of other stories such as The Wheel in Space and The Mind Robber.

The Doctor had previously been seen to do a space walk, in a helmet with oxygen but no face visor, in Four to Doomsday, where he claimed to be able to survive this environment for up to 6 minutes.

Next time: monk-y business in the Vatican...

Inspirations: Knock Knock

A fairly straightforward one this, as it's another attempt to do a "haunted house" story in the series. There had obviously been an element of this previously in Blink, and more so in Hide. 

Specifically, what inspired writer Mike Bartlett were those odd creaks which people hear in the middle of the night, or when you are supposedly all on your own in an empty building... 

Promoting the series Doctor Foster, Bartlett had mentioned that he was a Doctor Who fan, and this was noted by the series' script editor - Lindsey Alford - who then mentioned it to her husband, who just happened to be its executive producer Brian Minchin.

Steven Moffat assumed that the writer would be far too busy to submit anything as his own series had a second season commissioned, but Bartlett insisted he would make the time.

Sent away to think of an idea, he hit upon creaking floorboards, and pondered if these were caused by something within the very fabric of a house. There would be something hidden in the attic, and the walls would move.

Always a fan of exploiting a common fear for the show, Moffat was pleased with the concept.

Thoughts about the housing crisis led him to plot a story about a group of people forced to move in and share - only to be picked off one by one by whatever lurked within the house. When given details about new companion Bill, who was to be a university student, it made sense to have the sharers a group of her student friends moving in together.

Bartlett had once lived in a big Victorian house in Yorkshire as a student, which had a basement that looked like a dungeon.

The menace in the walls would be giant insects, and Bartlett named these Dryads - after the wood nymphs of Greek mythology.

"Drys" is the Greek word for oak, and it was initially believed they were specifically spirits of those trees. Tied to a particular tree, they died when it died, so they weren't immortal. Their appearance changed with the seasons.

Two notable Dryads were Daphne - who was transformed into a laurel tree to avoid the unwanted attentions of Apollo - and Eurydice, wife of Orpheus, whom he tried to bring back from the Underworld.

Bartlett envisioned actors Mark Rylance or Stephen Rae for the Landlord - a mysterious man in a brown suit. In the end, he would be gifted David Suchet, famous for his long-running TV role as Poirot, which ran from 1989 to 2013. (Peter Capaldi had featured in the third season story Wasp's Nest).

Suchet accepted the part without even asking what it was, so pleased was he to appear in the series.

The look came from a man who used to visit his parents, but the brown suit fits with the general colour palette of the episode. It was intended that the house would have wooden doors and wood-panelled walls.

The thing in the attic would prove to be a wooden woman - inspired by The Sandalwood Girl. This 1985 children's novel was written by Sheila K McCullagh, and Bartlett had been reading it recently to his son.

In the first draft, the house would give up all its victims at the end - going back every 30 years, to 1937. The Doctor would offer to get them all back to their own times in the TARDIS. The first disappearances, according to the second draft, were in 1927.

Until late in the day, the house was to have been restored at the end of the episode, but this was changed in order to explain why Bill would be back staying with her foster mother again later.

One of Bill's new flatmates is named Harry, and it was originally intended that he would be the grandson of former companion Harry Sullivan. It was decided that this was too obscure a reference and was dropped - despite Harry being referred to fairly prominently in Inversion of the Zygons only the year before...

Harry was then going to become an ancestor of one of the colonists from the earlier episode Smile.

At one point the Doctor talks about "going up the wooden hill" - meaning up the stairs to bed. (The full saying is "up the wooden hill to Bedfordshire"). He had previously used this phrase to Ace in Ghost Light, which Bartlett considered another inspiration.

The building is described by student Shireen as a "Scooby Doo house", as in the spooky mid-1970's cartoon series featuring a Great Dane and a bunch of teenage mystery solvers. 

Larry Nightingale had described Wester Drumlins in the same way in Blink - and the same location was used both in that story and in this, though a different section of the building.

David Suchet would be surprised to discover that his family had rented the property for a holiday a couple of years before.

Telling the students about the time he helped out musician Quincy Jones, the Doctor mentions that he had a Klarj Neon Death Voc-Bot for a bassist - presumably a reference to the ones seen in The Robots of Death.

Next time: The Suits get you every time. Bill encounters zombies - in space. The Doctor turns a blind eye...

Inspirations: Thin Ice

The phrase "on thin ice", meaning to be in any potential danger, first appears in an essay by Ralph Waldo Emerson in 1841.

As a story set around a particular historical event, that's our obvious starting point.

As already mentioned, new companions tended to get the same trio of introductory story types, with the third one being a trip into the past.

Steven Moffat had been impressed with Sarah Dollard's previous story - Face The Raven - and asked her if she had any other ideas. 

A friend of hers had done a lot of research on the last great Frost Fair on the Thames for another project, which had also intrigued Dollard. 

Originally the Doctor was to have taken Bill to visit it deliberately, but this was later amended to be a random visit by the TARDIS.

The river Thames used to freeze over frequently, with the first ever recorded mention back in Roman times.

Henry VIII is said to have used a sleigh instead of his usual barge to travel between Westminster and Greenwich in 1536.

The river used to be slow moving, the climate colder thanks to the Little Ice Age, and London Bridge's 19 piers interfered with the flow of the Thames - ideal conditions for it freezing over during particularly severe winters.

Staging a fair on the ice, in the centre of London, took place for the first time in 695. Others followed in 1608 (the first time the setting up of stalls and entertainments on the ice was actually called a Frost Fair), 1683-84, 1716, 1739-40, 1789, and finally in 1814.

The freeze of 1683-4 was notable for lasting nearly two months. An entire street was built across the Thames from Temple to Southwark, with hackney coaches running its length. When the thaw finally came, a ship moored against a riverside pub broke free and pulled the building down, killing 5 people.

The last time a significant section of the Thames froze over was the winter of 1962-63, in the upper part of the river.

These Fairs ended due to climate change and the demolition of London Bridge in 1831, followed by the building of the Victoria and Albert Embankments which channelled the river quickly through the city.

It is the Frost Fair of 1814 which interests us, however.

The previous episode - Smile - had ended with the Doctor and Bill emerging from the TARDIS to find themselves not where they expected to be - back at St Luke's University. Instead, they had seen ice, and an elephant wandering towards them from out of the fog.

This was one of the most famous events of the 1814 Fair - the ice so thick that an elephant could be led across it by Blackfriars Bridge. The freeze began just after Christmas, 1813, and lasted until 7th February 1814.

As well as food and drink stalls, there was dancing and nine-pin bowling, and a dozen or so printers set up their presses on the ice to print souvenir pamphlets about the Fair.

When the thaw came, a number of people drowned.

The Doctor fails to mention to Bill that he visited this very event with River Song, when he got Stevie Wonder to sing to her for her birthday - as mentioned by her in A Good Man Goes To War.

The Big Finish audio "Frostfire" claims that the 1814 freeze was caused by an alien, whilst different Doctors and companions had visited earlier Fairs in novel and comic adventures.

Whilst the setting for Thin Ice might be the Frost Fair, the actual story revolves around a gigantic serpentine creature trapped beneath the ice in the Thames, which is being exploited by a ruthless peer of the realm during the Industrial Revolution.

The idea for a serpentine entity came from Steven Moffat observing that the Thames, as it appears in the opening credits to EastEnders, looks like a giant snake.

The showrunner was also interested in doing a story involving a sea monster, thinking of movies such as The Beast From 20,000 Fathoms (1953) and The Giant Behemoth (1959).

Lord Sutcliffe is the villain of the piece, and he has somehow discovered that the creature's excrement can be processed to become a fuel source, capable of providing great heat.

In a nutshell, the Industrial Revolution came about in Great Britain due to the coming together of several key components - readily available resources of water, wood, coal and iron ore, plus the men (and it was mostly men) who had either the vision or the money to exploit them. These were the inventors, and the businessmen / land owners who were wealthy enough to commission the ideas of the former and put them into money-making practice.

Wood, coal and charcoal could only burn to a certain temperature, and to create certain metals this wasn't high enough. New methods of producing power were invented, in the hope that greater, more sustainable, temperatures could be achieved, and so stronger metals could be produced.

There's a lot more to the Industrial Revolution than that, of course, but this is the key element as it relates to this story.

On top of his exploitation of the creature, Sutcliffe plans to bring about the destruction of the ice whilst the Fair is in full swing, as a means of feeding it and so increasing its "output".

And he's a racist to boot.

Whenever a new companion makes their first visit into the past, they often speak about two issues - the "if I step on a butterfly will it change the future?" scenario (as in Ray Bradbury's A Sound of Thunder short story of 1952); and - if they are Black - will they be carted off as slaves. 

We saw this first with Martha Jones on her visit to Elizabethan London in The Shakespeare Code, and it gets a mention again here. In both cases, the Doctor points out that the city has always been more cosmopolitan than people think, and we see a wide range of ethnicities amongst the background cast.

The Doctor here talks about the "whitewashing" of history, though the danger is that the programme is actually presenting an idealised version of the past which ignores the racism of the time.

The idea that Sutcliffe is somehow atypical of early Victorian Britons, of any class, in his attitudes is a bit of a nonsense.

The children whom the Doctor and Bill encounter are orphaned street-urchins who make their living scavenging and stealing - which naturally makes us think of the juvenile pickpocketing gang recruited by Fagin in Oliver Twist or, The Parish Boy's Progress, by Charles Dickens (1838). One of the gang - a boy nicknamed "Spider" - steals the sonic screwdriver and is subsequently killed after being pulled under the ice, eaten by the creature. This is an extremely rare instance of a child being seen to die in the series. His bright red hat stands out, which is presumably a directorial nod to the girl in the red coat in Steven Spielberg's Schindler's List.

The Doctor tells the children the story of Der Struwwelpeter, or Shock-Headed Peter - an 1845 German children's book. Written by psychiatrist Heinrich Hoffman, this comprised ten stories which each had a cautionary element, where naughty behaviour has a nasty consequence for the children involved.

Steal sonic screwdrivers - get eaten by sea monsters...

Pie Men were a common sight in Georgian and Victorian London, walking the streets with a tray of freshly baked pies - usually meat but often eel - on their head or strapped to their waist. The best known example in literature is the one met by Simple Simon in the nursery rhyme. Unfortunately, the quality of the contents of the pies varied considerably - hence their cheapness.

Not perambulatory, another famous fictional pie seller is Mrs Lovett, who made her wares from the victims of Sweeney Todd, The Demon Barber of Fleet Street...

Next time: Who's there? The series' oldest gag gets an airing as the Doctor helps Bill move into her new accommodation. No jokes about wooden acting, please...

Inspirations: Smile

As with previous new companions up to this point, the usual pattern of (mostly) contemporary Earth setting, followed by far future adventure, followed by a trip to a historical period, was decided on for Bill. Smile would be her future story.

The reason we concentrate on just her and the Doctor for much of the running time was simply to establish their relationship.

Writer Frank Cottrell-Boyce had previously contributed the story In the Forest of the Night in Series 8 - a fantastical premise which would surely have seen Chris Bidmead's head explode on DWM's "Bidmead-O-Meter", which rated stories with utterly daft science.

For his next submission, he decided to provide something based much more on real science.

Preparing for an anthology of science fiction short stories, Cottrell-Boyce had approached a scientist working at the Jodrell Bank radio telescope, to discuss how humans might in future colonise other planets. He was advised that this would likely be done by sending robots on ahead to prepare the way.

Noting the preponderance of dystopian futures laid out in the genre, the writer wanted to present a utopian society, in which the lives of the human colonists were regulated by robots and artificial intelligence, working to their benefit. This then led to thoughts about what rights these robots / AI would have were they to become self-aware.

Steven Moffat was pleased with this as a backdrop to a story, which does not surprise as "AI gone wrong" had already been used by him on more than one occasion. It had taken over from the "mad computer" style of story, variations of which ran throughout the classic series.

Cottrell-Boyce had noted the increasing use of emojis which were being employed more widely. He saw these as a new language, which had begun to grow beyond social media.

Peter Capaldi and Moffat both explained on Doctor Who Extra that they neither used nor fully understood emojis, but Jenna Coleman had used them all the time, rendering some of her texts to them near unintelligible.

The Emojibots were originally envisioned as simple boxes with arms, with a screen on the upper surface on which they would communicate by displaying emoji icons. They were not intended to have any human-like form.

As well as the Emojibots, Smile features nanobots named Vardies. This derived from the scientist Dr Andrew Vardy, who researched swarm robotics at the University of Newfoundland in Canada. He had attended a conference in 2013, one of whose aims was to link scientists with authors. Vardy and Cottrell-Boyce collaborated on a story the following year.

Insect-like in the final programme, they were originally intended to be hedgehog-like in appearance.

The writer named the colony world Erewhon - an anagram and near palindrome of "nowhere". There are two possible inspirations for this. 

The first is the 1872 novel Erewhon: or, Over the Range, by Samuel Butler. This told of a utopian country and acted as a satire on Victorian society. One aspect of this was that the sick were branded as law-breakers, as they could not uphold the general happiness expected of the inhabitants.

Then there is News From Nowhere (Or an Epoch of Rest), written by William Morris in 1890 which told of another utopian society.

As the working title for Smile was "News From Nowhere", we can assume the latter - though Morris may have himself been inspired by Butler's work.

In the finished story, it is only the colony ship which is named Erewhon, and the planet has the designation Gliese 581D. Gliese 581 is a red dwarf star around which a "Super Earth" exoplanet was discovered in 2007 - Gliese 581c. It is 20.4 light years from Earth in the constellation of Libra, makes a complete orbit in 13 days, and has one hemisphere permanently facing its star. In terms of surface conditions, it is thought to resemble those on Venus.

An Earth colony in which the populace are forced to be happy is not a new idea for the show. The concept featured in The Macra Terror, and in The Happiness Patrol.

At one point the Doctor quotes David Bowie: "I'm happy, hope you're happy too", from his 1980 hit Ashes to Ashes.

The Doctor states that the Scots seek independence on every planet colonised. A referendum was underway at the time of writing. Scotland going it alone after abandoning Earth had also been mentioned in The Beast Below.

Steadfast is said to be a MedTech One grade. 'MedTech' was the designation given to Vira in The Ark in Space - suggesting that these colonists may have left Earth not long before the solar flares which led to the setting up of space station Nerva as a sanctuary.

Ralf Little had featured in the movie 24 Hour Party People - which was also written by Cottrell-Boyce.

The colony ship is said to have a Fleishman Cold Fusion Engine. This was named after Martin Fleishman, a chemist who had claimed to have discovered cold fusion.

Noting how the seats in the TARDIS are so far from the console, Bill asks the Doctor if he has stretchy arms like Captain Fantastic of Marvel's Fantastic Four. She also asks if they have to wear seatbelts whilst in flight. The TARDIS had been seen to have safety belts, which attached to the console itself, in Timelash.

Next time: The Doctor and Bill return to Earth and meet with a frosty reception...

Inspirations: The Pilot

Not to be confused with the unscreened version of An Unearthly Child, which is often referred to as "The Pilot" - but for Steven Moffat it was designed to fulfil the same purpose of allowing people to start watching the series. The term employed was a "soft reset".

This wasn't something new for the series. As well as the obvious relaunches - the 1996 TV Movie and Rose - there were also soft resets with The Tomb of the Cybermen and Spearhead From Space in the classic era, designed to act as jumping-on adventures for new viewers. The Eleventh Hour also sees the series dispense with all associations from the previous RTD era.

The only character already established here, other than the Doctor, is Nardole, who has appeared in the last two Christmas Specials - but knowing who, or what, he is isn't important right now.

Clara has gone, and River Song's story has finally been wound up. You'll recall that Moffat hadn't known he was going to be producing a sixth season - expecting Chris Chibnall to take over with his own new companion, and he had cleared the decks to facilitate this.

Time has moved on for the Doctor and he is now lecturing at a university - something he has been doing for quite some time we learn. There's a big metal vault in the cellars which has something to do with why he is here. There's a Police Box in his rooms, and on his desk are a mug full of sonic screwdrivers, and photographs of his granddaughter Susan and River Song - his first and last to date companions. The desk items are there to please the existing fans and to establish that this is a continuation of a series which began in November 1963, without alienating new viewers.

We find out what this is all about through the eyes of the new companion, Bill Potts, who is the first openly gay companion in the series (Captain Jack slept with anything). She serves in the university canteen but wants to better herself, and the Doctor sees the potential in her - electing to allow her to join his lectures whilst tutoring her privately. She is the agent through which the new viewers get into the series.

This was inspired by a performance of Educating Rita which Moffat had seen in Glasgow. This 1980 Willy Russell play told of the relationship between a working class Liverpudlian hairdresser and her older, boozy college professor, and how each ultimately has a positive impact on the other. It was adapted for the cinema in 1983, starring Michael Caine and Julie Walters.

The plan was to have a funnier companion, straight talking, who would ask the sort of questions which the audience might ask and view things through their eyes. They would also be shown to have watched sci-fi films and TV series, as Moffat had noted that people in Doctor Who rarely acted like they had seen time machines and aliens on screen. For instance, the Doctor tells Bill that the TARDIS has a "cloaking device", just as he had done in the TV Movie - but here he's using language someone who has seen Star Trek would understand.

As well as her sexuality, it was decided that Bill should also be non-white, following criticisms about lack of diversity and representation in Doctor Who and other popular dramas, made by Sir Lenny Henry in a BAFTA speech.

Casting for Bill - a name Moffat heard David Tennant call Billie Piper during production on the 50th Anniversary story - carried a codename. This was "Meantown" - an anagram of 'Woman Ten', as in the female companion for the tenth series. Meantown was also a placeholder title for the story in its earliest form.

Three audition pieces were written, which all found their way into the series in one shape or form. The first was the companion talking about someone she fancied who she serves in the canteen (a boy at this stage). The second was their introduction to the TARDIS interior after escaping from some robots. The companion argued that there was no protection inside a small box made of wood. The third scene was set in a corridor in a Dalek city, where the companion made comments about the monsters' stair-climbing capabilities and kitchen / bathroom appliance design elements.

Once cast, Pearl Mackie wanted to view some old stories but Moffat discouraged this - feeling her lack of knowledge about the series and its tropes would benefit her performance.

The working title for the story became A Star In Her Eye - a reference both to the fact that Bill's would-be girlfriend Heather has an actual star shape in one of her eyes, and to Bill's growing admiration for the Doctor.

The Doctor hangs an "Out of Order" sign on the TARDIS door - just as he did in The War Machines.

The biggest fan-pleasing moment is when the TARDIS arrives in the middle of a Dalek battle. We see that they are fighting the Movellans. The Dalek-Movellan war was first introduced in Destiny of the Daleks, and its outcome formed the background to Resurrection of the Daleks.

Bill was first introduced to the public in a mini-episode titled Friend From The Future, filmed on this futuristic corridor set and featuring a Dalek.

Early in the development of the season, Moffat considered the occupant of the mysterious vault to be either Missy or Davros. Fan speculation was that it might be Susan, after seeing her photograph on the desk - the reasoning behind which was that she had been placed in the vault to protect her from the Time War.

Next time: AI Goes Wrong No.632. Yes, it's the return of one of Mr Moffat's favourite story ideas. The Doctor and Bill visit a beautiful colony planet, but find little to smile about...

Story 276: Twice Upon A Time

In which the Doctor, refusing to regenerate after being mortally wounded by Cybermen, finds himself at the South Pole. It is December 1986, and out of the icy fog emerges one of his earlier selves - his first incarnation. He has just come from his first encounter with the Cybermen, and is battling against his own impending regeneration.

Whilst the two argue over what they are doing here, time seems to stand still as they see snowflakes suspended in the air. A British Army Captain of the First World War then wanders towards them, unaware of how he came to be here. The last he remembers was being trapped with a German soldier in a foxhole - about to kill each other - when time had stood still for him as well. He had then been approached by a bizarre female figure who appeared to be composed of glass.

The Doctor takes them both into his TARDIS. The First Doctor is not impressed with it, or with the fact that this is his future incarnation.

A gigantic spacecraft appears overhead and it lowers a huge hydraulic claw which seizes the TARDIS and pulls it aboard.

They hear a voice asking them to come outside to the Chamber of the Dead.

The Doctors are offered a gift in return for handing over the Captain - Bill Potts. The Doctor knows that she cannot be real, but she insists that it is the real her.

The Doctors discover time-travel technology of advanced design.

The glass woman appears and explains that the Captain must be returned to the time and place of his death. The First Doctor is given a glimpse of his future selves, learning that he will be known as the "War Doctor", which appals him.

The Doctor manages to open the hatch through which they were brought on board and they use the claw cable to descend to the ice beneath. They take to the First Doctor's TARDIS and dematerialise.

The Doctors wish to know who this glass woman is and what her motives might be. She looked like she was based on a humanoid original so the Doctor decides they must seek out the greatest database in the universe - and he knows where to find it.

The ship arrives on the planet of Villengard, amongst the ruins of its famous weapons factories. A ruined tower is under attack from Daleks, many of which have lost their casings. The Doctor will go there himself as he knows the occupant. In the TARDIS, it is revealed that Bill is really the glass female in disguise.

At the top of the tower the Doctor finds the Dalek which he had previously nicknamed "Rusty".

It has carried on its campaign against its own kind and has amassed a huge databank of knowledge in the meantime. It is able to identify the woman they seek as Professor Helen Clay. She helped found the Testimony Foundation which collects the memories of the dead and allows them to speak again through glass avatars. In this way, everyone has a chance to live on after death.

There is nothing evil behind what she seeks with the Captain.

Time is made to stand still once again, and the two Doctors travel with the Captain to the WWI battlefield. Here the Doctor learns that the man is a member of the Lethbridge-Stewart family - the Brigadier's grandfather.

He has returned to his foxhole, resigned to die, but the Doctor has nudged time on a few minutes. It is Christmas 1914, and the fighting stops for the festive armistice. The Captain is saved.

The First Doctor departs, ready now to face his regeneration after seeing a glimpse of his future.

Before "Bill" departs, she gives the Doctor a final gift. He sees Nardole - and Clara, memories of whom are returned to him.

He, too, is now ready to face his regeneration. With the TARDIS in flight he regenerates into a female form. The ship goes out of control and the new Doctor falls out of the open doors...

Twice Upon A Time was written by Steven Moffat - his final contribution to the series at time of writing - and was first broadcast on Monday 25th December 2017.

Moffat had thought that his final story, and that of Peter Capaldi's Twelfth Doctor, was to be The Doctor Falls. This was the second half of an epic series finale featuring the return of the Mondasian Cybermen and of the Harold Saxon incarnation of the Master, with the Doctor repeatedly blasted by Cybermen, Bill Potts transformation and departure, and the two incarnations of the Master killing one another. Ordinarily, this would have been an ending, but it would prove to be just a step towards the final end for actor and writer, which would be prolonged until Christmas.

Moffat had expected his successor, Chris Chibnall, to launch his iteration of the series, with the new female Doctor, at Christmas 2017. Christmas night was the prime time of prime time, a slot which the series had won back in 2005 and held onto ever since - even when there hadn't even been a normal series that year.

However, Chibnall simply wasn't ready to produce a Christmas Special, and was contemplating doing away with them altogether anyway. Ratings for Christmas night were falling across the board, not just for Doctor Who. The soaps and the sitcom Mrs Brown's Boys were also seeing lower viewing figures, despite still maintaining good percentage scores.

In order to keep the slot, Moffat agreed to write one more story, and since the Doctor was already dying, he would prolong the regeneration for one more adventure and build an episode around this.

Moffat had earlier been asked about returning characters during a Comic-Con panel, when he stated that a meeting between the first and last Doctors - both famed for their grumpiness - would be a great idea.

Peter Capaldi then said that he knew who they could get to play him... This was David Bradley, who in 2013 had portrayed William Hartnell / the First Doctor in An Adventure in Space and Time.

The First Doctor had already been played by another actor, when Richard Hurndall had taken on the role for The Five Doctors. With the theme of regeneration already in place, the obvious storyline of two Doctors each facing their impending regenerations, but refusing to accept them, presented itself. This in turn led to the setting of the South Pole (scene of the Doctor's first regeneration at the conclusion of The Tenth Planet, which coincidentally featured the Cybermen). The meeting of the two Doctors would make for a special end of series cliff-hanger, and material was prepared to top and tail the Series 10 finale. The moment chosen was the sequence at the end of the fourth episode when the Doctor wanders off alone to the TARDIS before companions Ben and Polly can catch up with him, once he's already in the ship. Having just brought back the Mondasian Cybermen, the costumes existed to allow a recreation of scenes from the 1966 story, similar to those staged for the 50th Anniversary drama.

Several scenes were filmed, but few made it to the final episode. These were the introductory sequence where Hartnell's features blend into Bradley's, following the "Have you no emotions?" speech; and the regeneration itself, which existed as some 8mm off-air material and a clip preserved through inclusion in Blue Peter's coverage of Doctor Who's 10th Anniversary in 1973.

As a swansong for writer and actor, the episode was to include references to earlier stories. 

The episode opens with the caption "Previously on Doctor Who... 709 episodes ago", and we see footage from The Tenth Planet.

Other than those relating to the First Doctor, the biggest nod to the more recent past was the inclusion of "Rusty" - the Good Dalek - which had featured right at the start of Capaldi's tenure in the TARDIS, Inside the Dalek being only his second story. The location of Villengard went back to Moffat's very first story for the series in 2005. 

In The Doctor Dances the Doctor and Captain Jack discuss its weapon factories and their destruction.

Thanks to cuts we hardly see Ben (Jared Garfield) or Polly (Lily Travers).

On a personal note, two of Moffat's friends and fellow writers - the most prolific - just happened to also act. Mark Gatiss featured as the Captain, who we would subsequently learn is an ancestor of Brigadier Lethbridge-Stewart; and Toby Whithouse played his German army opponent.

Captain Lethbridge-Stewart lives in Cromer, the Norfolk town which his grandson will think UNIT HQ has been transported to in The Three Doctors.

The idea of the glass avatar (Testimony / Helen Clay being played by Nikki Amuka-Bird, who had featured in the Torchwood episode Sleeper) allowed for a reappearance of Pearl Mackie as Bill, and we also saw an image of Clara, with the Doctor regaining his memories of her. To round off the season, Nardole also appears to say goodbye to the Doctor, bringing all of their stories to a conclusion. It should be remembered that the Doctor was unconscious when taken into the TARDIS at the end of The Doctor Falls, so won't have been aware of the fates of Bill and Nardole. 

The Testimony Foundation is said to have been formed on New Earth. The Chamber of the Dead is able to show the First Doctor his future selves, allowing for clips of other Doctors.

One criticism of the story was the realisation of the First Doctor in terms of his old-fashioned attitudes. Bradley is given words which the First Doctor would never have uttered - but which the actor who played him might have done (e.g. the sexist remarks). It does seem as though Moffat has confused actor with character.

The series had been struggling to include festive components in its Christmas Specials, but the 1914 WWI armistice at Ypres, when troops from both sides ceased hostilities to party together and play football, hadn't been used so far. 

Overall, a nostalgic end to the Moffat / Capaldi eras. The actual story is quite weak, but that doesn't really matter. It's a farewell story in more ways than one, the end of an era. There are many who dislike (indeed, hated) what happened next, and this episode is now seen by some as the last of its particular line.

Things you might like to know:

• Peter Capaldi was invited to stay on when he learned that Moffat was leaving. It was only coincidence that the two left together. Capaldi decided that his three series were enough, and wanted to move on to other projects.
• This episode was so unplanned that both Pearl Mackie and Matt Lucas believed they had finished on the series and were pleasantly surprised to be invited back. Mackie was on holiday in the US when asked to return, and Lucas in Rome writing his autobiography.
• Rachel Talalay had already directed the Series 10 finale and was keen to get home, but Moffat and Capaldi together talked her into remaining in the UK to direct this story.
• Sadly, this was the final Doctor Who story to be designed by Michael Pickwoad. He passed away in August 2018.
• We see a ring drop from the new Doctor's hand just after she has regenerated - a nod to the same thing happening in Power of the Daleks.
• Unlike when Ten became Eleven, it isn't the regeneration which wrecks the TARDIS. It's only afterwards when the Doctor presses a button that the console explodes and it goes out of control - Chibnall intending, like Moffat before him, to have his own new console room.
• In the first draft there's a funny reference to Episode 3 of The Tenth Planet when the First Doctor seems to brag about his actions at Snowcap Base, to which the current Doctor remarks that all he did was have a big nap - Hartnell having fallen ill and the Doctor been written out of that episode, stuck unconscious in bed.
• As the Doctor sends a message to his future self, he quotes Terrance Dicks' famous words about the Doctor never being cruel or cowardly. He also advises never eating pears, which was on Ten's recorded to-do list in Human Nature.
• The Testimony Foundation was formed in the year 5 Billion and 12, which is before the events seen in either of the televised stories set on New Earth - so before the population was decimated by the mood virus.
• The difference in facial features of the First Doctor is put down to the early effects of the regeneration process. Their timelines being "out of synch" is the excuse why the Second Doctor will not remember any of these events.
• Testimony gives some of the titles which have been given to the Doctor, most of which we know of ("Destroyer of Worlds" was given him by Davros, for instance). However, two titles refer to stories we have never seen - "The Last Tree of Garsenon" and "The Butcher of Skull Moon".
• BBC VFX pioneer Bernard Wilkie's name appears on a label on the TARDIS console.
• Some of the set elements, like the brass columns, seen in the First Doctor's TARDIS are the original ones from 1963.
• Jon Pertwee's purple jacket from Planet of the Spiders is seen in the TARDIS. Capaldi was photographed by Mark Gatiss (who now owns it) wearing it in his trailer:

Story 275: World Enough And Time / The Doctor Falls

In which the Doctor decides to let Missy lead an expedition in the TARDIS. He will remain in the ship whilst she takes charge, accompanied by Bill and Nardole. This is all part of the Doctor's attempts to rehabilitate his old frenemy.

The ship is responding to a distress signal, and materialises in a control room. Missy must investigate and work out where they are, whilst the Doctor listens in. They have landed on the command deck of a vast cylindrical spacecraft - 400 miles long - which appears to be stationery in space, sitting on the edge of a Black Hole. Its engines are actually straining to move it slowly away and prevent it from being sucked into the phenomenon. 

A blue-skinned humanoid appears. Jorj is a janitor, and he has been on his own for two days, after his colleagues descended in a lift to the lower levels. He is armed, and appears frightened. He is concerned that one of the trio is human, which has attracted someone who is ascending in one of the lifts. Realising the danger he poses in this state, the Doctor emerges from the TARDIS. Jorj panics and shoots Bill, blasting a hole through her chest. The lift doors open and masked figures emerge, taking Bill away with them.

Nardole checks the monitors and discovers that there are thousands of life forms on the lower levels of this craft - the end furthest away from where they have landed.

There are hundreds of levels, each containing its own biosphere.

Bill wakes to find herself in a hospital, with a bulky artificial heart and lung unit attached to her chest. Exploring, she finds wards full of heavily bandaged figures. She is horrified to discover that they are silently crying out in pain. They long for death.

Looking out of a window she sees a nocturnal cityscape - a heavily industrialised area. A man named Razor introduces himself to her. He explains that she was brought to the lower levels of the spaceship some time ago. The other patients are in the process of being cured. He agrees to take her in.

In the control room, only a few seconds have passed since Bill was taken away. The Doctor realises that the ship is so large that time is moving at different speeds at either end of the craft, due to the effects of the gravitational pull of the Black Hole. Whilst minutes pass here, months or even years may pass at the other end.

The life signs Nardole detected are descendants of Jorj's original colleagues. The Doctor calls a lift, intent on searching for Bill. He is knocks Jorj out when he tries to stop the lift being called.

Bill is able to see the control room on a scanner Razor has set up, but the Doctor, Nardole and Missy look like they are frozen, with time passing so slowly in relation to where she is.

He explains that all of the people on this level are undergoing medical procedures in order to embark on a mass exodus to higher levels.

Ten years pass for Bill. Seeing that the Doctor has gone to the lift, Razor pretends to take her to the lift door on this floor to meet him. However, he delivers her instead to an operating theatre where she is told that she is to undergo a full upgrade.

The others arrive. Whilst the Doctor and Nardole go in search of Bill, Missy begins checking the computers. She discovers that this craft was a colony ship from the planet Mondas...

Razor appears and asks her if she recalls having been here before. He removes a mask to reveal that he is the disguised Master - her previous incarnation. 

The Doctor is confronted by a Mondasian Cyberman in the operating theatre, escorted by Missy and the Master. He is horrified to discover that the Cyberman is Bill...

The Doctor is taken up to the roof of the hospital where the Master explains that the Cybermen have evolved on this ship, and their 'Operation Exodus' is the planned invasion of the higher levels. They will take the entire ship, converting all the humanoids they encounter as they move towards the command deck. On Level 507 there is an agricultural zone, where the humanoid inhabitants struggle to prevent Cyberman incursions.

Missy knocks out the Master as Cybermen attack. They have always ignored non-human lifeforms, but the Doctor had altered their programming to make Time Lords just as vulnerable to conversion as human beings. The Doctor is blasted by a Cyberman, but Nardole arrives in a shuttlecraft. The three Time Lords and the Bill-Cyberman enter it and it takes off - punching its way up through a number of floors before crashing on Level 507.

Two weeks pass. Bill has been unconscious and wakes to find herself in barn where she meets a woman named Hazran. She looks after a group of children, and defends this level. She explains that Bill is kept outside their farmhouse as she frightens the children, and Bill sees her reflection in a mirror - that of a Cyberman. She had blocked her fate from her mind. The Doctor notes that she has managed to retain her human emotions.

As Nardole helps Hazran prepare defences against the full invasion, the Master leads Missy and the Doctor into the woods near the farm. The latter is concealing that the injury he received from the Cyberman on the roof was actually terminal, and he is holding back his regeneration. The Master shows them both a lift entrance, and suggests they use it to find the Doctor's TARDIS and escape. His own ship is disabled on the hospital floor, its dematerialisation circuit burnt out. Missy carries a spare - due to a vague memory of these events.

The Doctor thinks they will never reach the TARDIS alive, and he wants to stay and help defend Hazran and the children. He asks his fellow Time Lords to join him. The Master and Missy refuse, and set off for the lift.

A number of booby-traps destroy some of the Cybermen, many of whom have evolved into more advanced versions. The Doctor orders Nardole to guide Hazran and the children to an upper level, as he plans to destroy this one with all the Cybermen concentrated in one location - even though he is likely to perish himself in doing so.

At the lift, the Master and Missy betray each other. She has taken on board much of what the Doctor had done to rehabilitate her, whilst he hates what the Doctor has done to his future self. They kill each other. The dying Master descends to the hospital level to find his TARDIS, where he will regenerate into her, whilst she is left for dead in the woods - the Master having ensured that she can no longer regenerate.

Nardole leads Hazran and the children to Level 502, whilst the Doctor and Bill battle the Cyberman army. He is shot several times, but manages to blow up the Level. Bill finds his body and takes it to the TARDIS. 

The water entity Heather appears, never having lost contact with Bill. The pair will travel the universe together, with Bill transformed into an ethereal being like her.

The Doctor wakes up in the TARDIS, and emerges to find himself in a bleak snowy wasteland. He refuses to regenerate. A figure approaches through the icy fog, and he is shocked to see that it is his own first incarnation...

World Enough And Time / The Doctor Falls were written by Steven Moffat, and first broadcast on 24th June and 1st July, 2017.

They brought the tenth season of the revived series to a close, and marked the final appearances (to date at least) of Michelle Gomez as Missy, and John Simm as the Master. The story also introduced David Bradley as the First Doctor, after the actor had previously portrayed William Hartnell in the 50th Anniversary drama An Adventure in Space and Time.

The episodes were also supposed to mark the departure of Peter Capaldi as the Twelfth Doctor, regenerating at the conclusion due to multiple blasts by Cyberman attackers. 

Steven Moffat had assumed that his successor as show-runner was going to write the 2017 Christmas Special, presumably introducing the Thirteenth Doctor. However, Chris Chibnall informed him that he was going to pass on writing a Christmas episode and would not be providing his first story until the Spring of 2018. Not wanting to see the series lose the prestigious Christmas night prime-time slot, in which had fared well in the ratings, Moffat hurriedly altered the ending of The Doctor Falls so that it would segue into a new final story for Capaldi, to be screened on 25th December.

Capaldi had earlier stated that the original Cybermen were one of his favourite monsters from the classic era of the series, and he'd love to see them make a return. These were the costumes designed by Sandra Reid for The Tenth Planet in 1966, characterised by blank cloth faces. He had suggested to Moffat that they could do the costume much better nowadays with current materials. 

By way of a thank-you to his departing star, and because he himself was leaving, Moffat elected to write a story which included the Mondasian Cybermen. This would also act as a Cyberman origins story - an idea first mooted by their co-creator Gerry Davis back in the mid 1980's. This time it was Capaldi who suggested it - possibly inspired by the Big Finish audio Spare Parts. 

Moffat re-read Davis' Doctor Who and the Cybermen which demonstrated how the Cybermen simply wanted to survive. The two newer versions of Cyberman could be included as the creatures would be seen to evolve.

Cybermen had featured in a number of series finales since Moffat took over - or the penultimate episode of the season: The Big Bang, Closing Time, Nightmare in Silver, Dark Water / Death in Heaven, and Hell Bent.

The story would be seeing the conclusion to the Missy story arc - and the departure of Gomez. To make this series finale even bigger, Moffat decided to deliver a "Two Masters" tale, bringing back John Simm as the previous incarnation. He had last been seen in The End of Time Part II,  leaving the show with David Tennant and Russell T Davies. At the time he had claimed that he would not be returning - as Gomez was to claim on the occasion of her departure.

As a nod to the Delgado and Ainley incarnations, Simm sported a goatee beard this time. The use of disguises was another of their traits.

The Master states that before he left Gallifrey, the Time Lords cured him of the persistent drumming in his head - hence why it hasn't affected Missy of the Sacha Dhawan incarnation. They no longer have the X-ray skeleton effect which we saw in The End of Time.

Presumably the Master had stolen his new TARDIS from Gallifrey, as he had not been seen to possess one since The Mark of the Rani (though not seen on screen, he must have used it to get to 18th Century Northumbria). Missy's failure to recall any of the events here, involving as they do her earlier self (apart from her unconsciously carrying of a spare dematerialisation circuit) can only be explained by the trauma of their mutual destruction of each other, though it isn't terribly clear.

It was originally intended that Simm's return would be a closely guarded secret, but then the BBC released the news as they thought he would be spotted on location. As it was, no-one did notice, so the return was spoiled by the production team themselves.

Other than the rogue Time Lords already mentioned, there are two additional guest artists of note. Playing Hazran is Samantha Spiro, who had recently played Carry On... star Barbara Windsor in biographical drama Babs, having previously played her in an earlier biopic titled Cor, Blimey! about the relationship between Windsor and Sid James. And Stephanie Hyam returns from The Pilot to play Heather.

Jorj is played by Oliver Lansley, and the surgeon and nurse who upgrade Bill are Paul Brightwell and Alison Lintott respectively.

Overall, an excellent pair of episodes that would have made for a fitting swansong for Peter Capaldi's Doctor. Lots to please long term fans with references to the classic series and even spin-off material. The Mondasian Cybermen may be slightly over-designed, in comparison with the originals, but Moffat gives them a great origins tale. Recently voted the top Capaldi story in the DWM 60th Anniversary polling.

Things you might like to know:

• "World enough and time" is a line from the 1681 poem To His Coy Mistress, by Andrew Marvell. In it, the poet promotes living life to the fullest as death may be just round the corner. It was published posthumously.
• One of the reasons John Simm agreed to return to the programme was because he was disappointed not to have been involved in the 50th Anniversary.
• It was assistant director Michael Williams who coined the phrase "Mondasian Cybermen". 
• Moffat addresses Cyberman continuity by claiming that whilst they evolved on Mondas, they came into being on many other worlds as well, quite independently. Wherever there are humanoids struggling in adverse conditions, there is the potential for them to resort to cybernetic implants to survive.
• Planet 14, mentioned in The Invasion as somewhere the Cybermen once encountered the Doctor, has long been puzzled over by fans. Is it the Moon? Is it Telos? Is it the scene of some unscreened adventure? According to this story, it's simply another planet where Cybermen evolved.
• Marinus is also mentioned, tying in with a DWM comic strip - "The World Shapers" - in which Voord evolved into Cybermen.
• The Doctor also mentions places where he has defeated the Cybermen in the past, which include Telos (Tomb of the Cybermen and Attack of the Cybermen), the Moon (The Moonbase) and Voga (Revenge of the Cybermen).
• According to this story, it is the handlebar attachments on the Cybermen which act as the emotional inhibitors. In The Tenth Planet they simply held the head lamp in place.
• Amongst the silly names Missy uses for Bill and Nardole, she calls them "Exposition" and "Comic Relief", which just happen to be two story functions of the companion character.
• The scenes in the snowy wasteland with David Bradley were shot during the making of the Christmas Special, and only edited into these episodes just before broadcast.
• Earlier regenerations are referenced. The Doctor talks of Sontarans perverting the course of history as he wakes up in the TARDIS (as with the Fourth in Robot); says "No!" - the final word of the Second Doctor; and "I don't want to..." - as in Ten's "I don't want to go".