The Doctor and Romana head to the planet Calufrax in search of the second segment of the Key To Time. Inexplicably, however, the TARDIS lands on Zanak. The Doctor discovers that Zanak is a pirate planet, materialising around other worlds and reaping their mineral wealth. The leader of this operation is the crazed Captain, who is prepared to take Zanak onto its next conquest: Earth.

Douglas Adams was interested in writing from a very early age, and by the time he reached college had gravitated towards comedy. In the mid-Seventies, Adams was mentored by Graham Chapman, and briefly wrote for (and appeared in) Monty Python's Flying Circus. He also contributed to programmes like Out Of The Trees and Doctor On The Go. Adams continued to have difficulty securing regular work, however, and was often forced to take odd jobs to make ends meet. Adams was also interested in science-fiction, and during this period (around 1976) submitted ideas to Doctor Who script editor Robert Holmes. Amongst these was a wildly convoluted and comedic storyline called “The Krikkitmen”. Holmes rejected Adams' suggestions, but saw enough potential in them that he encouraged Adams to continue forwarding writing samples to the Doctor Who office.

In 1977, Adams was commissioned by BBC Radio for the pilot episode of a potential serial called The Hitchhiker's Guide To The Galaxy. He forwarded the script to Holmes' successor on Doctor Who, Anthony Read, who felt that Adams' material was very strong. With Adams still unsure as to whether The Hitchhiker's Guide To The Galaxy would proceed beyond its initial script, he agreed to work with Read in devising a new storyline for Doctor Who.

Adams brought several ideas to the table. Predominant amongst these was the notion of a planet which is being mined by the Time Lords, who use a giant aggression-sapping machine (disguised as a statue) to pacify the natives. One Time Lord becomes trapped in the statue and absorbs all the aggression, inducing him to turn against his people. He causes the mining devices to hollow out the planet and now plans to make it dematerialise and reform around Gallifrey. Additionally, Adams had conceived a drug addiction allegory, about a company which preys on people who fear death by offering machines which can slow time for them -- but at an exorbitant price. The company goes bankrupt, however, leaving one old lady in need of a source of fantastic energy. Producer Graham Williams, meanwhile, was keen on an adventure which featured a group of space pirates.

Although none of these concepts were viewed as capable of supporting a story by themselves, it was agreed that some combination of them might be more viable. The aggression-draining subplot was dropped (because of perceived similarities to the Season Fifteen serial The Sun Makers), but Adams mixed the remaining elements together to produce a very complicated plot (which may have been titled “The Pirates”). Nonetheless, Read was sufficiently happy with the result that on July 18th he commissioned Adams to develop it into a full storyline called The Pirate Planet.

As Adams refined his ideas for The Pirate Planet, the slow-time subplot became deemphasised. The Time Lords -- who would be appearing in the Season Fifteen finale -- were also excised, including the villain (whom Adams had envisioned as a Time Lord stuck in the slow-time field, in the midst of his last regeneration). At the same time, he came up with idea of the air car; this was a device he could employ to avoid scenes set in corridors, which he detested. Adams also concocted the Polyphase Avitron to make the Captain's scenes more interesting; for a time, he considered giving the robotic parrot dialogue like “Pieces of silicate!” Finally, Adams was given the green light to turn The Pirate Planet into full scripts on October 20th.

By now, however, he had also been contracted to provide a further five episodes of The Hitchhiker's Guide To The Galaxy, and was also producing Week Ending for Radio 4. As a result, progress on The Pirate Planet slowed considerably. As Adams' scripts gradually arrived, it became clear to Read that he would have to perform a considerable amount of editing on them. They were still too long and too complex, and Adams' inexperience with television drama meant that he had little idea of what could be accomplished within the limitations of the programme's budget.

To make matters worse, Head of Serials Graeme McDonald reacted very negatively towards The Pirate Planet, suggesting in a memo on March 14th, 1978 that the serial should be abandoned altogether. In particular, McDonald disapproved of the extremely comedic nature of the scripts, something he had also criticised when reviewing The Invasion Of Time at the end of the previous year. These objections came in spite of the fact that Williams had turned to humour in response to BBC management's directive that Doctor Who should steer clear of the scary, sometimes violent elements preferred by former producer Philip Hinchcliffe.

Williams had departed on holiday in February and had broken his leg in Madeira, Portugal, delaying his return to the Doctor Who office. Consequently, Read was temporarily acting as both producer and script editor, and found himself forced to defend The Pirate Planet to McDonald. Fortunately, Read had an ally in the director assigned to the adventure, Pennant Roberts (whose most recent work for the series had been on The Sun Makers). Read and Roberts argued that, because all of the serials of Season Sixteen were part of the Key To Time story arc conceived by Williams, it was virtually impossible to rearrange the recording order to accommodate a replacement. With just six weeks remaining before The Pirate Planet was due to enter production, McDonald relented.

On April 17th, John Leeson was contracted to provide the voice of K-9 for what was now designated Serial 5B. Two weeks later, location filming on The Pirate Planet began on May 1st with the recording of engine room scenes at Berkeley Nuclear Power Station in Berkeley, Gloucestershire. The next two days were spent at various sites in Gwent. On May 2nd, material at the minehead was filmed at the Big Pit in Blaenavon, while countryside sequences were completed at Coity Mountain, Bwlch y Garn in Ebbw Vale and the Monmouthshire Golf Club in Llanfoist (although the exact date of recording for the latter is uncertain). On the 3rd, the Zanak mountainside was actually Clydach Railway Tunnel in Daren-Felen, to which the production team returned on the 5th. In between, on May 4th, sequences at the base of the mineshaft were captured at Cathedral Cavern amongst the Abercrave Caves in Dan-yr-Ogof, Powys. Meanwhile, model filming took place at Shepperton Studios.

The remainder of The Pirate Planet was taped in BBC Television Centre Studio 6, with the first of two blocks occurring on May 22nd and 23rd. The first day dealt with material on the city street and in Balaton's house, together with special effects sequences, while the second day involved recording on the sets for the Mentiads' chamber and the aircar, as well as model shots of the city. Scenes in the city square were completed on both days, as was some footage on the bridge of the Vantarialis.

The second session in TC6 took place from June 3rd to 5th. Unfortunately, this block got off to a bad start when the labour unrest which had plagued both The Invasion Of Time and The Ribos Operation reared its ugly head again. This time, a dispute arose as to who was responsible for the operation of a caption scanner. The first two days dealt with the rest of the action on the ship's bridge and in the Metiads' chamber. Some effects scenes were also recorded on the 3rd, while the 4th saw additional taping in the inertialess corridor, the corridor outside the bridge, and the engine room entrance.

June 5th was given to material in the TARDIS console room and limbo area, plus Xanxia's chamber, the trophy gallery, and the remaining special effects shots. The Doctor's fall against the TARDIS console was a late addition to the script to explain the facial injury Tom Baker had sustained while making The Ribos Operation. Bizarrely, Vi Delmar agreed to remove her false teeth for her role as the methuselan Xanxia on this day only after negotiating an extra fee.

Adding to the strangeness of the studio sessions was the theft of the Polyphase Avitron prop; fortunately, this was discovered hidden in a nearby skip the following morning, so recording was not delayed. Nonetheless, the demarcation dispute did mean that Roberts was only just able to finish taping the duel between the Polyphase Avitron and K-9. On the other hand, production of The Pirate Planet was treated to a visit by Louise Jameson, who had played Leela until the end of the previous season. Jameson stopped by to visit Roberts as well as her successor, Mary Tamm, whom she knew from their days together at the Royal Academy of Dramatic Arts.

• Doctor Who: The Handbook: The Fourth Doctor by David J Howe, Mark Stammers and Stephen James Walker (1992), Virgin Publishing, ISBN 0 426 20369 8.
• Doctor Who: The Seventies by David J Howe, Mark Stammers and Stephen James Walker (1994), Virgin Publishing, ISBN 1 85227 444 1.
• Doctor Who Magazine #253, 2nd July 1997, “Archive: The Pirate Planet” by Andrew Pixley, Marvel Comics UK Ltd.
• Doctor Who Magazine Special Edition #9, 22nd December 2004, “I'll Put You Together Again” by Andrew Pixley, Panini Publishing Ltd.
• In-Vision #33, September 1991, “Production” edited by Justin Richards and Peter Anghelides, Cybermark Services.