Writer
Chris Boucher was commissioned to write the story (his third for the series) on 2 May 1977. He delivered the first episode just two days later, the final one being submitted on the 17 June. He also took inspiration from the work of archaeologist
Louis Leakey who had been excavating human remains for many years until his death in 1972. Boucher named Colby's dog Leakey as a tribute to him, although later realised that people would miss the reference and assume the name came because "he pissed all over everything!" Boucher never wrote for the series again, immediately after this becoming script editor on ''
Blake's 7'' for four years and as the BBC didn't want anyone working on two shows at the same time. Boucher would write another script concerning an alien gestalt entity, for the 1981 ''Blake's 7'' episode "Rescue". Producer
Graham Williams had worked with director
George Spenton-Foster previously on
Z-Cars and chose him to direct this serial due to his experience with night filming. Spenton-Foster would direct one more time for the series in the following year's
The Ribos Operation. Script editor on the serial was
Robert Holmes in his final assignment. During the work he was trailed by incoming editor
Anthony Read, who would subsequently take up the role solely for the next story in production order
Underworld (the following transmitted story
The Sun Makers having been recorded before
Image of the Fendahl). Read had been a television producer but was asked by BBC Head of Serials
Graeme McDonald to be script editor to which Read refused until he learned it was for
Doctor Who. The exterior scenes were shot on the
Stargroves estate in
Hampshire, which was owned by
Mick Jagger. The same location had been used during the filming of
Pyramids of Mars. Filming began on Monday 1 August 1977 and continued until the following Thursday. This included two night shoots for the serial on the Tuesday and Wednesday evenings. The first night's filming was disrupted when the generator caught fire. Another generator had to be ordered from London and arrived at 4am. Filming at the estate had only been agreed on the 26 July – less than a week before filming began, with the instruction (as had been the case with "Pyramids of Mars") that no effects or explosions were to be undertaken given that the property was a
Grade II listed building. Two days after filming was completed Tom Baker and
Louise Jameson attended the world's first ever
Doctor Who convention in London. Following rehearsals, studio recording for the serial began on Saturday 20 August and was completed on 6 September 1977. Jameson regards this as one of her best stories due to it being written by Chris Boucher, who had created Leela. It was, however, during the making of this serial that she decided to leave at the end of the series.
Wanda Ventham, playing Thea, had previously appeared in
The Faceless Ones, and would subsequently appear in
Time and the Rani, her three appearances each being ten years apart: 1967, 1977 and 1987. Ventham had in fact auditioned for the
James Bond film
Goldfinger, but lost out to
Shirley Eaton and therefore was excited to be painted gold in this serial, as would have been the case in
Goldfinger. She also had to wear a dark wig as the human Thea, as Spenton-Foster thought that her natural blonde hair would lose credibility as a scientist.
Denis Lill, cast as Fendelman, was the production team's second choice after actor
Anthony Bate became unavailable. Lill would subsequently appear in the 1984 story
The Awakening and was Ventham's husband in the sitcom
Only Fools and Horses.
Scott Fredericks had played Boaz in 1972's
Day of the Daleks and was later cast by Spenton-Foster in the ''Blake's 7
episode "Weapon" alongside Graham Simpson who also appears in this story. Derek Martin had appeared a number of times in Doctor Who
as an extra, going back to 1965 and subsequently as a stuntman with the HAVOC group, who had taken part in a number of early serials featuring Jon Pertwee as the Doctor. This was his first and only work on the series as an actor. Geoffrey Hinsliff who played Jack would go on to appear in the 1979 story Nightmare of Eden''. ==Broadcast and reception==