Donna Noble has come to realise that she made a mistake when she declined the Doctor's offer to travel with him in the TARDIS. Now she finds herself seeking out every hint of the unusual and the unexplained, in the hope of running into him again. Her plan succeeds when both she and the Doctor begin to investigate Adipose Industries, a company run by the sinister Miss Foster which offers a suspiciously effective diet pill. They discover that Miss Foster is actually using the human race as the breeding ground for alien creatures called the Adipose -- and millions of lives are at risk.

By the start of 2007, Doctor Who executive producer Russell T Davies had decided to make a change to his regular line-up of characters. Martha Jones, played by Freema Agyeman, was a new companion who would be introduced during the Season Twenty-Nine premiere, Smith And Jones. However, as work on her episodes progressed, Davies had come to feel that the character would need a break from the TARDIS, in order to provide a realistic timeframe for her to resolve her unrequited romantic feelings for the Doctor. Martha would make several appearances in the spin-off show Torchwood at the start of 2008, and then return for a number of Doctor Who episodes later that year, during Season Thirty.

However, this meant that a new companion would need to be developed to accompany the Doctor. This character would be introduced in the first episode of Season Thirty which, as was now traditional, would be written by Davies himself. However, tradition was a less compelling force in television production than pragmatism. While Doctor Who season premieres normally went before the cameras early in the recording schedule, this pattern would change for Season Thirty in order to make allowances for the time constraints under which Davies was writing his scripts. The new companion's introduction would instead be recorded closer to the middle of the production calendar.

Russell T Davies intended to pair the Doctor with a 30-something companion named Penny Carter

As a result, Davies had only barely begun to develop his ideas for the season premiere when plans for the new companion underwent a major change. He had intended to pair the Doctor with a thirty-something companion named Penny Carter, who was based in part on Donna Noble, the character portrayed by Catherine Tate in the 2006 Christmas special, The Runaway Bride. During March 2007, however, it was learned that Tate herself was interested in returning to Doctor Who, and a deal was rapidly put together for her to co-star as Donna in all thirteen episodes of Season Thirty.

To this point, Davies' ideas for the season premiere were fairly vague. He had considered an untitled story idea set in suburban London, with a spaceship sealing off a section of the city under an enormous dome while an alien was hunted through the streets. By the end of March, Davies had decided to drop the spaceship element, and was instead working on an untitled storyline about a portal to another world hidden within a dilapidated old house. He wanted to include scenes involving hundreds or even thousands of alien monsters using computer software of the type recently employed to great success in movies such as 2002's The Lord Of The Rings: The Two Towers.

In early April, however, Davies realised that -- since Donna was not a new character who had to be introduced from scratch -- he could write a very different sort of season premiere. This inspired the idea of the Doctor and Donna separately investigating strange goings-on in an office block, constantly missing each other by a hair's breadth and thus not meeting until halfway through the adventure. Initially, Davies considered basing the narrative around cosmetic surgery: Botox-like injections would be revealed to contain alien spores that could burst and transform the victim into a monster. By July, his focus had shifted to the weight-loss industry, with pills turning human fat into sentient creatures called Adipose, from the scientific name for body fat. Davies still wanted to depict a massive number of aliens as a visual hook for the season premiere and so, in mid-July, he began coordinating with visual effects firm The Mill to achieve sequences involving hundreds of Adipose on screen at the same time.

By the start of August, however, it was clear that a script for the season premiere would not be ready in time for the planned production dates. Originally, the debut episode was to be made by director Colin Teague alongside James Moran's The Fires Of Pompeii as the season's third recording block. Moran's adventure already boasted a number of challenges -- not least several days' filming in Italy -- and so it was decided to give Davies more time by cleaving the block in two. The Fires Of Pompeii would now comprise Block Three on its own, while the premiere would form a new Block Four. Consequently, a different director was required for Davies' episode; this would be James Strong, who had recently completed the 2007 Christmas special, Voyage Of The Damned.

The escape via a window washer's cradle had been planned for the Doctor and Martha in Smith And Jones

With the pressure to complete his script now somewhat alleviated, Davies was finally able to begin writing on August 30th. His first draft for what would eventually become known as Partners In Crime was completed on September 6th. At this point, the villain of the piece was called Miss Rattigan, a surname Davies had previously used on the soap opera Revelations. She later became Miss Foster, which Davies felt better encapsulated her parental role. Davies also decided to acknowledge his original plans for the Doctor's companion by introducing an investigative journalist named Penny Carter. One of the episode's key set pieces -- the Doctor and Donna's escape via a window washer's cradle -- had previously been planned for the Doctor and Martha in Smith And Jones, but had been trimmed due to that script's excessive length.

Eager to provide Donna with a tether to modern-day Earth, Davies decided that her parents, Geoff and Sylvia Noble, would feature prominently in Season Thirty. By early September, actors Howard Attfield and Jacqueline King had agreed to reprise their roles from The Runaway Bride. Attfield's agent cautioned Davies about his client's health, as he had recently undergone chemotherapy to treat cancer.

Meanwhile, Davies had also been considering the inclusion of a more high-profile return at the end of Partners In Crime. From an early stage, he had hoped that Season Thirty would culminate in the return of several significant characters who had appeared since Doctor Who's television revival in 2005. These plans took on a new impetus when it was decided that this would be Davies' last opportunity to write a season finale. In lieu of a full slate of episodes during 2009, there would instead be a handful of specials, which would draw his tenure on Doctor Who to a close. As such, Davies wanted to make Season Thirty's conclusion as big as it could possibly be. Key to this was the return of Rose Tyler, played by Billie Piper; the former companion had last appeared in the Season Twenty-Eight finale, Doomsday, in which she became trapped in a parallel universe, seemingly forever.

Now, however, Davies had devised a way to bring Rose back and, in March, Piper confirmed that she was willing to appear in as many as four new Doctor Who episodes. Davies began contemplating the possibility of adding a brief glimpse of Rose to Partners In Crime. To preserve the surprise for viewers, the sequence would either be edited out of any preview tapes, or else replaced with analogous footage in which Rose did not appear. Davies was still mulling over this idea in August, when it was learned that Piper would be on honeymoon during January 2008 -- overlapping with the intended filming dates for the two-part season finale. Davies feared that he would have to rework the season's storylines to omit Rose, but executive producer Julie Gardner was able to rejig the schedules of all involved in order to accommodate Piper's availability. At this point, it was also agreed that the surprise scene in Partners In Crime should proceed. However, it would have to be structured in a manner which would allow it to be filmed during the making of Turn Left, the first episode in which Piper would make a fully-fledged return to the series.

Location filming for Partners In Crime was almost entirely confined to Cardiff. On October 4th, many of the scenes outside and within Stacey's home were taped at Waterloo Gardens and Stallcourt Avenue. The next day, a house on Glan Rhymni was used for both Stacey's bathroom and Roger's residence, while shots of the Adipose Industries van were captured on Newport Road. Strong's team then stood down for the weekend, although some of the cast and crew spent October 7th making a charity mini-episode entitled Time Crash.

Work on Partners In Crime resumed on October 8th, when the Adipose Industries press conference was filmed at the Odeon Cinema. Earlier that day, at Grangemoor Park, Strong had recorded the scene in which Donna spoke to her father while he was stargazing. Sadly, it was now clear to all involved that Attfield's health was much poorer than had previously been understood. In fact, he had not completed chemotherapy; his treatments were still ongoing, and his cancer remained aggressive. Attfield himself was frank about his long-term prospects: although Geoff was meant to appear in The Sontaran Stratagem / The Poison Sky -- the next story in production -- and then in the final three episodes of the season, there was no certainty that he would be able to participate. As a result, Davies began considering the possibility of writing the character's death into the season arc, with Donna becoming a stronger person after dealing with the loss of her father. It was also suggested that Attfield might record all of his scenes for the rest of the season within the next few days, despite the fact that most of them were not yet written.

While these discussions were taking place, the sequences on the roof of Adipose Industries were filmed on October 9th and 10th at the British Gas Building; stairwell material was also taped there on the latter day. The 11th and 12th saw a suite in the Dominions Arcade double as Miss Foster's office. The only location work for Partners In Crime outside Cardiff came on October 13th, when Picture Finance in Newport provided not only an area with sales cubicles, but also staffmembers to serve as extras in these scenes. After a break on the Sunday, action in the corridors of Adipose Industries was filmed on the 15th, at the Millennium Stadium.

On October 15th, Bernard Cribbins accepted the offer of a recurring role for Season 30

Meanwhile, Attfield's situation had deteriorated. His body's weakened condition had resulted in a broken leg, and his wife advised the production team that he would not be able to continue on Doctor Who. Out of respect for Attfield, Davies immediately ruled out casting a different actor as Geoff. Instead, he proposed dropping the character altogether and reviving one of his initial ideas for Penny Carter, who would have had a close relationship with her stargazing grandfather. Producer Phil Collinson suggested that they approach Bernard Cribbins, who had had a cameo role in Voyage Of The Damned as a newsvendor named Stan. Although he had only spent a single night on the production, Cribbins had thoroughly enjoyed appearing in Doctor Who and, on October 15th, he accepted the offer of a recurring role for Season Thirty. Davies immediately amended the script for Partners In Crime, replacing Geoff Noble with Cribbins' character, who was now renamed Wilfred Mott. New dialogue would acknowledge that Geoff had passed away sometime after the events of The Runaway Bride.

Work on October 16th began on the standing TARDIS set at Doctor Who's regular studio facilities in Upper Boat. Also recorded on this day was the material outside the wine bar visited by Sylvia and her friends, which was actually Bar Icon on Charles Street. On the 17th, a residence on Nant-Fawr Road served as the Nobles' home, while Donna convinced the Doctor to take her aboard the TARDIS at Crockherbtown Lane. Work at the latter location also included a remount of the Doctor meeting Donna on the stairwell, necessitated by a lighting problem which had afflicted the original version. October 18th concentrated on scenes outside Adipose Industries, represented by both the British Gas Building and Crockherbtown Lane. Strong also shot footage in the Adipose Industries foyer at the 1 Kingsway office building. The 19th and 20th were spent at Upper Boat dealing with effects shots -- particularly for the sequence involving the window washer's cradle -- and various inserts.

The last day of principal photography for Partners In Crime was October 23rd, when the Fat Cat Cafe Bar posed as the interior of the wine bar, and the material in the Adipose Industries lavatory was completed at nearby Tiger Tiger. Four weeks later, on November 19th, two sequences were remounted: a scene in Stacey's house at Waterloo Gardens, and Donna boarding the TARDIS, which was now shifted to Havelock Street. On the 20th, material at the Noble residence was re-recorded at Nant-Fawr Road. Having originally featured only Donna and Sylvia, the new footage incorporated Wilfred as well. Cast and crew then returned to Havelock Street to shoot the separate arrivals of Donna's car and the TARDIS near Adipose Industries. The day concluded with the filming of a new version of the hilltop material at Grangemoor Park, now featuring Wilfred in Geoff's place; related inserts were taped on November 27th at Lady Mary Allotments. On November 29th, the scene in which Donna spoke to Rose was recorded at Franklen Road. An alternative version, with an extra taking Piper's place, was also shot. Finally, on December 18th, a pick-up shot of Donna arriving in the Adipose Industries foyer was taped at Upper Boat.

Partners In Crime would be dedicated to Howard Attfield's memory

Sadly, Attfield succumbed to his cancer on October 31st. In tribute, it was decided that Partners In Crime would be dedicated to his memory. Also acknowledged in the episode's credits was the contribution of visual effects artist Stephen Regelous. A few years earlier, the New Zealander had developed software called Massive for Peter Jackson's The Lord Of The Rings movies, which provided independent animation for large numbers of computer-generated characters. It was these sequences which had helped inspire Davies to write Partners In Crime in the first place, and the services of Regelous and Massive were secured to create the scenes of the thronging Adipose.

For the fourth year in a row, the new Doctor Who season was earmarked for a premiere close to Easter Saturday which, in 2008, fell on March 22nd. For a time, it was thought that Partners In Crime would be transmitted on April 12th. However, in mid-March, it was decided to avoid the premiere of Britain's Got Talent on ITV and instead bring the broadcast forward a week, to April 5th. To Davies' chagrin, Doctor Who was given a 6.20pm start time, which was significantly earlier than had typically been the case since the programme's return in 2005. Partners In Crime was positioned after a celebrity edition of the quiz show Weakest Link, and led into the reality competition I'd Do Anything, which boasted John Barrowman -- who had played Captain Jack Harkness in both Doctor Who and Torchwood -- as one of the judges.

Despite Davies' concerns about the impact of the early timeslot on the episode's viewing figures, Partners In Crime was watched by a healthy audience of 9.1 million people. Surprisingly, this was better than any debut episode since Rose in 2005. Far from happenstance, this was a sign of things to come in 2008...

• Doctor Who Magazine Special Edition #20, 19th November 2008, “Episode 1: Partners In Crime” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who: The Complete History #58, 2017, “Story 189: Partners In Crime”, edited by Mark Wright, Hachette Partworks Ltd.
• Doctor Who: The Writer's Tale by Russell T Davies and Benjamin Cook (2008), BBC Books.