Inspirations: Partners In Crime

Catherine Tate had enjoyed working on the 2006 Christmas Special - The Runaway Bride - but it wasn't immediately intended that she would return later to become the full-time companion. 

Russell T Davies liked Donna Noble's personality, and initially created a new companion named Penny Carter, who was a journalist. She would have been recently dumped by her boyfriend, and would share many of Donna's characteristics.

Realising that what RTD wanted was a character like Donna, his colleagues simply suggested why not just get Donna. Tate's availability was checked and it was found that she could be free for the Series 4 production dates.

In the meantime, RTD continued to develop Penny's first story. It would be set on contemporary Earth. Penny's mother - Moira - would be a lottery winner, who was also unlucky in love, and her grandfather would have a passion for astronomy. They would hail from the North of England, rather than be yet more native Londoners.

The episode's monster was always intended to be a CGI one. The opening scene would have featured Penny throwing a surprise party for her boyfriend, only to catch him with another woman. Storming off, she would have come across the TARDIS.

When Tate let it be known that she was happy to return as Donna, only a few elements of this first episode (draft title "Second Chances") were retained.

A journalist named Penny was included in Partners in Crime. Donna was unlucky in love, and lived with her mother, who was already established. As she already had a father as well, he was given the astronomy interest.

Bringing back an existing character allowed RTD to skip the introductions. He was able to show how Donna had been influenced by her brief encounter with the Doctor, and was investigating things that might have interested him, which might lead them to meet again. The episode could therefore hit the ground running, with both Doctor and new companion already involved in the main plot.

It would be funny to prolong the meeting - with both characters continually just missing bumping into each other. When the time finally came, it would coincide with the reveal of the main villain and their plan, and would overshadow this.

RTD had by now realised that the best series opener was a lightweight one, with a lot of humour but also some impressive CGI effects.

The sequence with the window cleaner's cradle was one which RTD had hoped to use in earlier episodes. It almost featured in Smith and Jones, and back when he first pitched his vision of the revived series to the BBC he had used this scene as an image, but with the characters being menaced by a Pterodactyl.

For the main plot, the never-ending fad for dieting and weight-loss provided the backdrop. Every month some new diet was promoted, 'guaranteed' by some minor celebrity. Botox injections were a big thing at the time, and RTD thought about there being some alien element hidden in the Botox, which would turn people into mutant creatures. RTD's dislike of cosmetic surgery and peoples' obsession with beauty had already led to the creation of the Lady Cassandra in 2005.

The aliens would be called the Adipose - 'adipose' being bodily tissue which stores fat (not fat itself).

Originally envisaged as looking like the finished version but giant sized, RTD thought it would be funnier to have them as little babies - based on the Pillsbury Doughboy advertising character, a giant version of which had featured in the Ghostbusters film. It was RTD who suggested the inclusion of a single fang - to suggest a more fierce adulthood for the creatures.

This then led to the human villain helping them being a sort of foster mother, so calling herself "Foster". Always intended to be a female figure, she was initially going to be called Rattigan, and she was inspired by Jo Frost, presenter of the Supernanny TV series. (RTD had previously used the name Rattigan for a family in his bizarre ITV soap Revelations, and he would use it this year for a character in the Sontaran story).

Director Peter Jackson had employed a new AI computer programme to animate the vast armies who battle each other in LOTR: The Two Towers. This was called Massive, and allowed figures to act randomly and independently of each other in large crowd scenes.

Miss Foster's demise - temporarily frozen in mid-air before plummeting to the ground - was inspired by Roadrunner cartoons, as it was a situation Wile E Coyote often found himself in. 

The spaceship was deliberately designed to mimic the Mothership from Close Encounters of the Third Kind.

The Doctor uses his "John Smith" alias yet again - first used for him by Jamie in The Wheel In Space, and by the Doctor himself in Spearhead From Space.

To hide her identity, the script referred to the woman whom Donna told about the car keys as "Bin Girl". RTD had quite early on decided to have Rose Tyler make an unexpected appearance in the first episode, with the scene omitted from preview copies to ensure a surprise on broadcast.

Howard Attfield, who played Donna's father Geoff, was ill. It had been known that he had cancer and was undergoing treatment, but it quickly became apparent that his condition was worse than the team were led to believe. He was able to film all of his scenes for this episode - the ones set at night on the allotment with his telescope. Soon after, his condition worsened and it was plain he couldn't carry on. The team had enjoyed working with Bernard Cribbins on Voyage of the Damned and wanted to do more with him. It was decided to invite him to take on the role of Donna's grandfather, Wilf, who would replace Geoff. This would be the same character as the newspaper vendor, who had never been named on screen. Penny Carter's grandfather had originally been an amateur astronomer. The allotment scenes were all re-recorded with Cribbins.

Attfield died soon after filming, and this episode went out with a dedication to him.