Writing The Wheel in Space is the fourth
Doctor Who story to feature the Cybermen, after
The Tenth Planet (1966),
The Moonbase and
The Tomb of the Cybermen (both 1967). The Cybermen were created by
Kit Pedler (unofficial scientific adviser to the production team) and
Gerry Davis (story editor) as a replacement for the
Daleks, the alien villains created by
Terry Nation. Nation planned to capitalise on the Daleks' popularity by developing Dalek
spin-off media, so he temporarily withdrew the villains' rights from the programme. Plans for a new Cybermen story were temporarily halted in August and September 1967 by a minor dispute over the Cybermen's rights and royalties. Pedler eventually accepted a halfshare of royalties, and in September he began developing the serial with the production team. In December, Nation was approached regarding a serial potentially featuring both Daleks and Cybermen, but he refused to allow the villains to appear together. This was the first Cybermen serial not written by either Pedler or Davis. As Davis had left the programme to work on
The First Lady, and Pedler lacked experience in writing for television, veteran
Doctor Who screenwriter (and original story editor)
David Whitaker was called upon to develop Pedler's notes into a finished script. The serial's working title was
The Space Wheel. Pedler wanted the space station to be depicted with a degree of scientific accuracy. On 14 December, incoming story editor
Derrick Sherwin formally commissioned Whitaker to write a six-part serial titled
Dr Who and the Wheel in Space. It follows the "base-under-siege" format which constitutes the majority of the
Second Doctor's television stories. Not long before filming, many of the characters' names were changed by director
Tristan de Vere Cole to give the space station's crew a more diverse range of nationalities. This is first time the Doctor uses the alias "John Smith", which he would often use as the
Third Doctor.
Casting as companion
Zoe Heriot. As
Deborah Watling decided not to renew her contract in late 1967, her character
Victoria Waterfield was written out of the programme in
Fury from the Deep. Sherwin envisaged a scientifically-minded young woman to replace Victoria's role. Writer
Peter Ling suggested the character be named Zoe. Interviews began in early January 1968. Following a camera test held at
Lime Grove Studios during recording for
The Web of Fear (1968), actress
Wendy Padbury was cast as astrophysicist
Zoe Heriot. Padbury admired
Patrick Troughton's acting and she turned down a role in the film
The Prime of Miss Jean Brodie in order to play the Doctor's new
companion.
Frazer Hines' then-girlfriend
Susan George also auditioned for the role. The second episode was written to accommodate Troughton's scheduled holiday. As a result, the Doctor is unconscious during the episode and played by body double Chris Jeffries. Director Tristan de Vere Cole cast many actors he had recently worked with on
Z-Cars. These include
Michael Turner, Clare Jenkins,
Kenneth Watson, Derrick Gilbert,
Donald Sumpter and Peter Laird. Jenkins, cast as Tanya Lernov, previously played Nanina in
The Savages (1966). She briefly reprised her role as Lernov in the final episode of
The War Games (1969).
Michael Goldie previously played Craddock in
The Dalek Invasion of Earth (1964). Watson also played Craddock in ''
Daleks' Invasion Earth 2150 A.D. (1966), the film adaptation of that serial. Sumpter later played Commander Ridgeway in The Sea Devils (1972) and Rassilon in "Hell Bent" (2015). He also played Erasmus Darkening in The Eternity Trap (2009), a serial from the Doctor Who
spin-off The Sarah Jane Adventures''.