Inspirations: Dinosaurs on a Spaceship

This was one of those stories where the title came first - inspired by the 2006 movie Snakes on a Plane - and the story was then built around it.

The writer handed this brief was Chris Chibnall, who had been responsible for the first two seasons of Torchwood and had written 42 under the RTD regime. For Moffat he had written the two part Silurian story for the previous series, and most recently had been the writer on the five mini-episodes which comprised Pond Life. Having been a lead writer on Torchwood, and run his own series - Camelot and Law & Order UK - he was given a pair of episodes to work on for this series, whilst Moffat was busy juggling Sherlock and Doctor Who.

As well as the title coming from a movie, the story also owed its origins to a discussion between the producers and the VFX company about what they might be able to achieve for the programme. 

The technology to create convincing dinosaurs on a TV budget had been proven a while back, with the landmark series Walking With Dinosaurs. This had led to shows like ITV's Primeval becoming possible, which had a heavy reliance on the creatures in a range of settings.

To make the story as exciting as possible, the spaceship of the title would be on a collision course with Earth - adding additional peril. At the same time, the producer - Marcus Wilson - suggested the use of some large, expensive robot costumes which had only ever been seen on the CBBC series Mission: 2110. Their exposure had, therefore, been limited, and it was felt that they could be included somewhere in the story.

When it came to populating the story with additional characters, Chibnall decided on two things - a look at Rory's family background, and the idea of the Doctor putting together an eclectic gang from his various travels to assist him. The latter had already proved successful in A Good Man Goes To War, which brought together what would later become known as the Paternoster Gang.

The Big Bang had shown Amy's parents, but we hadn't seen anyone from Rory's family. It was decided to incorporate his father into this gang. 

The gang would therefore have a mix of contemporary and historical people - both fictional and factual.

The latter was represented by Queen Nefertiti (c.1370 - c.1330 BC). She had famously vanished from history, her burial place still undiscovered, so any story could be made up about her. She also had a distinctive appearance. thanks to the antique famous bust in the Neues Museum in Berlin.

The fictional figure from the past was a big game hunter named John Riddell. He was based on similar characters from a host of old adventure series set in Africa (such as the Tarzan movies), and Alan Quatermain of H Rider Haggard's King Solomon's Mines (1885). One particular forebear is the character John Roxton, as played by Michael Rennie in George Pal's 1960 adaptation of The Lost World - another big game hunter confronted by dinosaurs.

This character was added later as he was originally going to be a cowboy, named Buffalo Jones. This idea was dropped when it was decided that a full-blown Western was going to be one of this series' stories.

The villain of the piece - Solomon - was inspired by the Somali pirates who were in the news plaguing shipping in the Indian Ocean, and subject of the 2013 Tom Hanks movie Captain Phillips.

Having reintroduced the Silurians to the series, Chibnall saw that it made sense to have them involved. As well as building subterranean shelters to avoid the expected disaster in prehistoric times, first mentioned in The Silurians, some had built a space ark to preserve more of their larger wildlife.

However, this went against established history for the creatures, who had never shown any space-going abilities. You have to ask why they simply didn't relocate their entire civilisation to another planet.

To play the lone representative, seen in ancient recordings, actor Richard Hope was cast. He had previously portrayed Malokeh in The Hungry Earth / Cold Blood, and The Wedding of River Song. Here he plays a character named Bleytal. This continued the trend that Silurians have genetic groupings where multi-generational members are identical in appearance.

(Malokeh's name had been derived from that of their creator, Malcolm Hulke).

At one point the Doctor claims to be a Sagittarian. This is the astrological star sign which covers 23rd November - birthdate of the series.

Next time: The Good, The Bad and the Cyborg...