The unmanned rocket Silver Carrier is millions of miles off course, drifting near a space station known as the Wheel. The Wheel's highly-strung commander, Jarvis Bennett, initially plans to destroy the rocket outright, but instead agrees to despatch some of his crew to investigate. When they discover the Doctor and Jamie on board the Silver Carrier, Bennett is convinced that the time travellers are saboteurs. But nobody is aware of the rocket's other passengers: the Cybermen. Using their Cybermats to wreak havoc aboard the Wheel, the Cybermen plan to use it as a stepping stone in their conquest of the Earth.

As 1967 drew to a close, interest in the Cybermen continued to ride high amongst the Doctor Who production team. In late summer, there had been a minor rights dispute raised by their co-creator, Kit Pedler. However, this was resolved in mid-September, and Pedler soon began discussing ideas for a new Cyberman adventure. On December 5th, permission was sought from Dalek creator Terry Nation to feature both monster races together in the same story. Nation's agent denied this request, although it was noted that further Dalek serials were not out of the question, as long as Nation was given the right of first refusal to write them. With the Dalek/Cyberman team-up having been vetoed, it was decided to instead proceed with a storyline developed by Pedler, which he apparently called “The Space Wheel”.

As with his earlier contributions to the series -- most recently The Tomb Of The Cybermen at the end of the last recording block -- there was no question of Pedler writing the scripts for “The Space Wheel” himself. However, his previous writing partner, story editor Gerry Davis, had now moved on from Doctor Who. In his stead, the programme's original story editor, David Whitaker, was recruited to turn Pedler's ideas into full scripts. Whitaker had just completed work on The Enemy Of The World, which was transmitted partway through Doctor Who's fifth season. He was commissioned on December 14th for what was now called The Wheel In Space; Pedler himself received a belated commission for his storyline on the 18th.

The use of the alias “Doctor John Smith” would become a recurring gag in later stories

The scripts for The Wheel In Space introduced a new type of Cyberman: the Planner. Originally, this was envisaged as a regular Cyberman attached by wires to a special chair, as opposed to the non-humanoid design that would appear on screen. Also notable was Jamie's use of the alias “Doctor John Smith” for the Doctor, which was inspired by a stethoscope box bearing the label “John Smith & Associates”. This would become a recurring gag, with the Doctor occasionally adopting the pseudonym himself in later stories.

Around the same time, Deborah Watling informed producer Peter Bryant that she would be leaving Doctor Who with Fury From The Deep, the story which would precede The Wheel In Space into production. Story editor Derrick Sherwin was therefore tasked with devising a new companion to replace Victoria Waterfield; in contrast to Watling's nineteenth-century naif, Sherwin envisioned a scientific and intellectual prodigy. Peter Ling -- who was writing The Mind Robber, the final serial of the fifth recording block -- had used the name “Zoe” as a placeholder for the female companion in his scripts and, with Ling's permission, Sherwin christened the new character Zoe Heriot.

The production team's thoughts now turned to casting the new companion. A year earlier, it had been hoped that actress Pauline Collins would join the regular cast as Samantha Briggs, a character created for The Faceless Ones. However, when Collins declined the offer to remain on Doctor Who, Watling ultimately joined the series instead. Nonetheless, Bryant was still eager to bring Collins onto Doctor Who; he now offered her the role of Zoe, but without success. Instead, auditions for the part were held in early February 1968. Amongst the more than one hundred applicants was Susan George who, at the time, was dating Jamie McCrimmon actor Frazer Hines.

The role finally went to former Crossroads regular Wendy Padbury, who had to turn down a part in the film The Prime Of Miss Jean Brodie in order to play Zoe. On February 27th, Padbury was contracted for The Wheel In Space and the subsequent story, The Dominators, with an option for twelve more episodes; she was unveiled to the press via a photocall in Hammersmith Park, London on March 14th. Meanwhile, Hines had been issued a new contract on January 19th which covered the three remaining serials of the current block, starting with The Wheel In Space. On March 15th, Troughton's services were secured for another twenty-four episodes, from The Wheel In Space through to the early part of the sixth recording block.

The director assigned to The Wheel In Space was Tristan de Vere Cole. He had previously worked as a production assistant on The Gunfighters in 1966, but was now reluctant to return to Doctor Who. He soon developed a caustic relationship with Bryant, who felt that the director was circumventing the chain of command by communicating frequently with Kit Pedler and Derrick Sherwin; he was also unhappy with some of de Vere Cole's modifications to the script. Bryant would also later allege that de Vere Cole had exceeded his budget, and lodged a complaint with Shaun Sutton, who had recently been promoted from Head of Serials to Head of Drama. As production neared, de Vere Cole renamed several of the supporting characters in The Wheel In Space, largely to give the Wheel's crew a more international feel. Nell Corwyn became Gemma Corwyn, Tanya Lerner became Tanya Lernov, Tom Stone gained a promotion when he was rechristened Captain Leo Ryan, Harry Carby became Enrico Casali, and Ken became Chang.

The new Cyberman costumes proved problematic, and would have to be replaced for studio recording

From March 18th to 20th, de Vere Cole and his team filmed material for The Wheel In Space at the BBC Television Film Studios in Ealing, London. Their principal focus was on scenes involving the Servo Robot, as well as the Cybermats' lethal attack on Kemel Rudkin. The Cybermats were new props; unlike those used in The Tomb Of The Cybermen, these lacked eye pupils and antennae. On March 21st, model shots were completed at the BBC Television Centre Puppet Theatre in White City, London. Then it was back to Ealing on the 22nd for the spacewalk sequences. Two new Cyberman costumes debuted on this day, and quickly proved problematic. The exoskeleton added by costume designer Martin Baugh did not work well, and the new vinyl material became visibly wrinkled. It was agreed that the outfits would have to be replaced for studio recording; a spray-painted wetsuit now made up the body of the costume, while the exoskeleton was simplified and reconfigured. The unusual three-fingered gloves were retained.

Studio recording for Doctor Who was now taking place on Fridays to facilitate to the use of BBC Television Centre whenever possible. On April 5th, however, cast and crew temporarily returned to the show's old home of Lime Grove Studio D in Shepherd's Bush, London to make Episode One. The opening moments of this installment witnessed the final appearance of Victoria Waterfield, albeit only in material filmed for Fury From The Deep.

Patrick Troughton enjoyed a rare holiday during work on Episode Two. As such, he was absent from Wendy Padbury's in-studio debut, which took place in Television Centre Studio 3 on April 12th. During recording, Anne Ridler -- who played Gemma Corwyn -- barely made it through one scene after inadvertently damaging her sciatic nerve; as a result, she spent the rest of the serial on painkillers. At this stage, the scripts for the latter episodes were still being revised, in an effort to better develop Zoe's character.

Troughton returned for Episode Three, which was taped in TC1 on April 19th. On this day, equipment problems developed which meant that the Cyberman voice effect could not be created. Consequently, it was decided that the affected scenes would be remounted alongside Episode Four the following week, when production took place in TC3. However, limitations of time meant that only the cliffhanger ending was re-recorded on this day, with the other material deferred to a special session on May 3rd, prior to the recording of Episode Five that evening. The venue for the serial's last two installments was Riverside Studio 1 in Hammersmith, London, which had been Doctor Who's production home between 1964 and 1967.

The repeat of The Evil Of The Daleks would be incorporated into Doctor Who's narrative

Episode Six, recorded on May 10th, was scheduled to conclude Doctor Who's fifth season, although the production block would continue with both The Dominators and The Mind Robber, which would be held over to start Season Six in the autumn. In previous years, other programming -- often Laurel and Hardy short films -- had been scheduled to fill the void left by Doctor Who between seasons. For summer 1968, however, it was decided to plug the gap by repeating an old serial, in full, for the first time. On March 27th, Peter Bryant had obtained permission to rebroadcast 1967's The Evil Of The Daleks, and made the decision to incorporate it into Doctor Who's narrative. Twenty seconds from Episode Two of the Dalek serial was edited into the concluding moments of The Wheel Of Space, appearing on the TARDIS scanner as the Doctor warned Zoe about the dangers she might face by travelling with him.

With the broadcast of The Wheel In Space Episode One on April 27th, the BBC Saturday evening schedules were revised to replace The Monkees with another run of The Dick Van Dyke Show, which would now air after the news update which immediately followed Doctor Who. On May 18th, Episode Four was scheduled to air ten minutes later than usual, at 5.25pm, to accommodate the FA Cup Final between Everton and West Bromwich Albion. In the event, however, extra time pushed Doctor Who back to 6.00pm, preempting The Dick Van Dyke Show. Two weeks later, this was the planned schedule for the broadcast for Episode Six due to coverage of a highly-anticipated football match between England and West Germany. As such, the Doctor Who season finale aired after the news and weather, and immediately before Dee Time.

• Doctor Who Magazine #254, 30th July 1997, “Archive: The Wheel In Space” by Andrew Pixley, Panini UK Ltd.
• Doctor Who Magazine Special Edition #4, 4th June 2003, “Heroes And Villains” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who: The Complete History #12, 2018, “Story 43: The Wheel In Space”, edited by Mark Wright, Hachette Partworks Ltd.
• Doctor Who: The Handbook: The Second Doctor by David J Howe, Mark Stammers and Stephen James Walker (1997), Virgin Publishing.
• Doctor Who: The Sixties by David J Howe, Mark Stammers and Stephen James Walker (1992), Virgin Publishing.