When the space beacon on which the TARDIS has materialised is stolen by the cruel pirate Caven, the Doctor, Jamie and Zoe team up with an aging pioneer named Milo Clancy to recover their ship. Along the way, they must survive attempts by Caven to destroy them, avoid the Earth officials who have mistaken them for the thieves, and discover the truth behind the Issigri Mining Company's operations on the planet Ta.

Serial YY was originally intended to be Robert Holmes' The Krotons. When “The Prison In Space” -- the story assigned as Serial WW -- had to be abandoned at a late stage, however, The Krotons was pushed up in the schedule to replace it. Holmes quickly submitted a new idea to the Doctor Who production office, entitled “The Aliens In The Blood”. This was turned down, but Holmes soon set about developing a new idea which would serve as a futuristic homage to the Western genre. This was more to the liking of script editor Terrance Dicks, and a storyline was commissioned under the title of The Space Pirates on November 9th, 1968. It was planned to be a six-part adventure, although Holmes recalled that he had originally envisioned the story as running only four episodes.

At this point, Peter Bryant was still Doctor Who's producer, but former script editor Derrick Sherwin was taking on more and more of Bryant's responsibilities as he prepared to take over the post himself. Bryant was also experiencing a bout of poor health. A fourth member joined the production team at around this time in the form of Trevor Ray, Dicks' new assistant. Ray was also an actor; one of his credits was for an episode of Z Cars written by Sherwin. As work began on The Space Pirates, however, Dicks was very busy working on the two stories which would go into production on either side of it -- he was rewriting The Seeds Of Death, and collaborating with Malcolm Hulke on the massive ten-part The War Games, which would be both the season finale and the last story of Patrick Troughton's tenure as the Doctor. Consequently, Sherwin returned to the script editor's post for The Space Pirates.

Despite concerns that the Doctor, Jamie and Zoe were not featured enough in Holmes' storyline, the scripts for The Space Pirates were commissioned on December 3rd. Early in the new year, director Michael Hart joined the production. This was Hart's only Doctor Who serial; he had also worked on series such as Z Cars and Softly, Softly and his career would continue with credits on programmes including Crossroads and Thirty Minute Theatre.

Filming began at the Ealing Television Film Studios on February 7th, 1969 with scenes at the beacon and in the tunnels on Ta; it appears that some of this may have been remounted on the 10th. The bulk of February 10th to 14th, however, was taken up with filming all the episode six scenes featuring the regular cast. This was because the lengthy The War Games would require an extra week of filming, which would occur during the week normally devoted to part six of The Space Pirates. Patrick Troughton, Frazer Hines and Wendy Padbury had been specially contracted for these sessions on January 23rd.

Unfortunately, a portion of the film shot on the 14th was damaged during processing; a remount of some of the sequences set in the atomic fuel stores was consequently held on February 19th, requiring only Troughton's presence. The model shots, meanwhile, were accomplished by the Bowie Group in Slough. With Hart too busy working on the rest of the serial, special effects designer John Wood supervised this element of the recording.

Studio taping then began on February 21st. As was standard, each episode was recorded on consecutive Fridays. Part one was recorded in Doctor Who's usual home of Lime Grove Studio D. However, this would be the final episode taped in those facilities, marking the end of an association which dated back to 100,000 BC, the very first Doctor Who serial. Episode one also saw the addition to the crew of a floor assistant named John Turner. More commonly credited as John Nathan-Turner, he would become Doctor Who's producer a decade later.

The programme's new recording home was the more modern Television Centre Studio 4; part two was the first episode taped there, and was captured on 35mm film instead of videotape to make the editing process easier. The remaining installments of The Space Pirates were also taped in TC4 with the exception of part five, recorded on March 21st, which saw a temporary shift to TC6; this brought an end to the regular cast's involvement in the serial. The guest actors, however, returned to TC4 the following week to complete episode six.

The penultimate story of the Troughton era was also the last to feature a credit for producer Peter Bryant, although Bryant would continue to share the job with Sherwin until October (indeed, Bryant was originally intended to receive the producer's credit on The Silurians). At that time, Bryant was moved to the thriller series Paul Temple along with Sherwin and Ray; this was an expensive German coproduction which was finding itself in serious creative trouble. Bryant left the BBC in the early Seventies and became an executive producer for an independent production company. Bryant later became a literary agent. He passed away on May 19th, 2006, following an illness.

• Doctor Who: The Handbook: The Second Doctor by David J Howe, Mark Stammers and Stephen James Walker (1997), Virgin Publishing, ISBN 0 426 20516 2.
• Doctor Who: The Sixties by David J Howe, Mark Stammers and Stephen James Walker (1992), Virgin Publishing, ISBN 1 85227 420 4.
• Doctor Who Magazine #242, 28th August 1996, “Archive: The Space Pirates” by Andrew Pixley, Panini UK Ltd.
• Doctor Who Magazine Special Edition #4, 4th June 2003, “Paradise Lost” by Andrew Pixley, Panini Publishing Ltd.