Inspirations: Time Heist

This one is relatively straightforward. The writer, Steve Thompson, thought that a bank robbery involving time travel might make for a good storyline, and Steven Moffat agreed. It transpired that he had been thinking along the same lines, but was just waiting to develop the idea.

The heist would be made more complicated by the fact that, as well as the usual forms of security, this bank would employ telepaths who could detect guilty thoughts as soon as you walked through the door - so anyone planning to rob the place would be spotted immediately before they even had a chance to carry out any crime.

The telepaths idea would become a specific creature - the Teller - which not only detected guilt but could do something nasty about it. Thompson specifically wanted a real physical effects creature as he knew from previous stories he'd written that CGI used up too much of the budget.

Films and TV series about bank robberies have been around since the media were created, and have featured in many genres of story-telling. It's such an adaptable plot structure. A lot of Westerns revolve around bank or train robberies, as do comedies, science fiction films, and even swashbucklers like the Robin Hood movies that would see elaborate plans made to steal from the rich.

Indeed, quite often the robbers have been the heroes of the movie, despite engaging in criminal activity. Generally, in these cases, the people being robbed are usually presented as deserving to be robbed - either because they're so rich they won't miss it, or because they are even bigger criminals than our gang.

Classic heist movies are too many to mention, but a few I'd recommend are the original Oceans 11 (1960), where it's a luxury liner that's being targeted; The League of Gentlemen (also 1960) in which the gang are all British ex-servicemen who have fallen on hard times since leaving the army; The Killing (1956), in which it's a race track that is to be robbed, or The Italian Job (1969).

In terms of comedies, you can't do better than the Ealing movies The Lavender Hill Mob (1951) and The Ladykillers (1955).

(Golden rule: always watch the originals, not the lacklustre remakes).

Often with these films, especially pre-1960's, it was felt that criminals shouldn't be seen to get away with it, no matter how personable they come across, so they can end up either with the heist going wrong or the gang members end up in handcuffs - assuming they don't wind up dead.

Another inspiration is the close cousin of the heist story - the con artist tale. The BBC TV series Hustle showed a loveable gang pull off seemingly impossible jobs - always against someone who thoroughly deserves it - and we have to wait to a flashback sequence at the end to see just how they managed it.

Time Heist has to see the Doctor and his gang commit their crime for a morally justifiable reason. They can't possibly be doing it for wealth, so it turns out to be a rescue mission - to save the Teller's mate as they're the last of their kind. Each of the gang members also has to be participating for some personal reason - Psi to get his memories back, Saibra to get a drug which will help with her condition.

In the initial drafts for the story, Saibra was going to be a half human / half Zygon, hence her ability to shape-shift.

The story is remembered for the cameo appearances of some old monsters, some of which are a little odd as choices. We know that the Sensorite society can produce wrong 'uns like the City Administrator, but you don't really think of them first when it comes to criminals. Weevils are savage creatures of pure instinct, so also not the obvious candidates for master criminals. Other characters include Captain John Hart, Androvax, a Terileptil, the Trickster, an Ice Warrior, Kahler-Tek and the Slitheen. It looks like they just picked a bunch of characters from random episodes across the parent series and its spin-offs, with no real thought as to their appropriateness. Oddest of all is Absalom Daak, who has only ever featured in comic book form - and he's a comic book character here as well. Couldn't they have got someone to dress up as him?

In order that the Doctor's gang can't be detected by the Teller, they employ Memory Worms to forget their ultimate intention. These were first introduced in The Snowmen.

Michelle Gomez was initially offered the role of Madame Karabraxos / Miss Delphox, but was unable to attend the audition, so asked Moffat to consider her for any other villainous roles...

Next time: First he gave you an episode in which the Doctor got a flat. Then he gave you a story in which the Doctor got a job. Now Gareth Roberts gives you a story in which the Doctor gets, er, a different job...