Returning to the Nerva Beacon, the Doctor, Sarah and Harry discover that they are thousands of years too early and must wait while the TARDIS drifts backwards in time. At this point, the Beacon directs interstellar traffic, warning spaceships away from a new satellite in Jupiter's orbit. This is all that remains of Voga, a world abundant in gold which was vital in ending the last Cyber war, and which is now home to a people riven by civil war. But the Cybermen are determined to strike back against Voga. They have unleashed a terrible plague aboard the Beacon as the first step in their plan... and Sarah is amongst the infected.

In 1972, producer Barry Letts had enjoyed ratings success when he brought the Daleks back to Doctor Who for Day Of The Daleks, following an absence of almost half a decade. Two years later, while planning the first season for Tom Baker's Fourth Doctor, Letts hoped to make lightning strike twice by resurrecting the programme's other prominent monsters: the Cybermen. Their last significant appearance in a Doctor Who serial had been in The Invasion at the end of 1968. To this end, Letts contacted former Doctor Who story editor Gerry Davis; he had co-created the Cybermen with Kit Pedler, but hadn't written for the series since 1967's The Tomb Of The Cybermen. A storyline entitled Revenge Of The Cybermen was commissioned on May 9th, 1974.

With an eye to making the most of Doctor Who's budget, Davis was asked to utilise the same setting -- albeit in a different time period -- as another planned Season Twelve adventure, Christopher Langley's “Space Station”. This would permit the same sets to be used across both serials. Davis' original notion was that, in his story, Langley's space station would be operating as an intergalactic casino. The Cybermen would be using their small, robotic Cybermats to spread a plague -- intended to be the same virus introduced in 1967's The Moonbase -- only for the Doctor to eradicate them using the casino's gold reserves.

The casino element was abandoned; the space station instead functioned as a relay beacon

On June 6th, script editor Robert Holmes contracted Davis to turn his storyline into full scripts, under the slightly amended title of “The Revenge Of The Cybermen”. At this stage, it was agreed to abandon the casino element, and it was soon decided that the space station would instead be functioning as a relay beacon. Meanwhile, Langley's scripts were dropped; the Cyberman serial would instead act as a sequel to The Ark In Space by John Lucarotti.

Hewing to Letts' original request for an inexpensive serial, Davis set most of the action aboard the space station, which became known as the Nerva Beacon. At this stage, the Nerva crew included a scientist named Anitra Berglund, and Warner was female. The Cybermen had been smuggled onto Nerva by Kellman before the story began, with the aim of destroying a gold-rich asteroid in the station's vicinity. The cliffhanger for Episode One featured a Cyberman concealed amongst spacesuits; this was inspired by the end of the second part of The Moonbase, in which a Cyberman was discovered hiding in a sick bay bed. Kellman had betrayed a group of miners (led by a man named Evans, and also including Jones and Williams) who had been marooned on the asteroid for a quarter of a century. They eventually killed him by dynamiting a tunnel. The Doctor destroyed the Cybermen by reprogramming the Cybermats and filling them with gold dust he retrieved from the asteroid.

Davis soon renamed his serial “Return Of The Cyberman”. Unusually, he also gave each episode its own title, even though this practice had been abandoned while Davis was a member of the production team. Since he lacked a concrete idea of how Tom Baker would portray the new Doctor, Davis essentially wrote the character in the vein of Patrick Troughton's Second Doctor, including the use of such signature elements as his 500-year diary.

Throughout the writing process, both Holmes and new producer Philip Hinchcliffe were concerned that Davis was pitching his scripts at an audience younger than that which Doctor Who now targeted. Hinchcliffe was also concerned that Sarah was largely extraneous to the action, and that Harry dominated Episode Four at the expense of the Doctor. Davis agreed to undertake a number of rewrites, which included eliminating Berglund and switching Warner's gender. Around the middle of September, the title reverted to “The Revenge Of The Cybermen”.

At the end of the month, however, it became clear that more money was available for “The Revenge Of The Cybermen” than had previously been anticipated. Hinchcliffe and Holmes decided that additional material should therefore take place on the asteroid, which could now been filmed on location. It was agreed that Holmes would substantially overhaul Davis' scripts. He replaced the tiny asteroid and its miners with a larger body inhabited by an alien race; several names for this world were considered, including Alanthea and Vega, before Holmes settled on Voga, after a mythical island sought by Christopher Columbus. At one point, Kellman perished when Lester sacrificed himself to kill the Cybermen, but his death was eventually brought forward to take place in the rockfall.

For the first time, the rank of Cyberleader was visually denoted by painting its helmet predominantly black

By the time production began, the serial's title was back where it started, as Revenge Of The Cybermen. The director was Michael E Briant, who had last worked on Death To The Daleks the year before. Briant decided against reusing the Cyberman costumes left over from The Invasion, which he felt to be antiquated. Four new outfits were made instead, and were again adapted from wetsuits. For the first time, the rank of Cyberleader was visually denoted by painting its helmet predominantly black.

Filming for Revenge Of The Cybermen began on November 12th, when all the model shots were completed at the BBC Television Centre Puppet Theatre in White City, London. For the scenes set on Voga, Briant decided to make use of the network of natural caverns at Wookey Hole, near Wells in Somerset. Inhabited by primitive man since around 50,000 BC, in modern times the caverns had gained a reputation for being haunted by a Dark Ages witch, now petrified as one of the rock formations. While scouting the complex, Briant's wife Monique discovered several Iron Age arrowheads in the sand, which she kept as a memento. Some crewmembers would come to believe that this precipitated a chain of strange occurrences and bad luck which beset the production. The first event attributed to this “curse” occurred later in the reconnaissance trip, when Briant encountered an individual dressed in spelunking gear late one night. The Wookey Hole staff had no knowledge of the man, and Briant came to believe that this was actually the ghost of an Irish potholer who had perished in the caves three years earlier.

The four-day location shoot spanned November 18th to 21st. On the first day, the small motorboats hired for use as the Vogan skimmers repeatedly broke down. Assistant floor manager Rosemary Hester suffered an attack of claustrophobia and had to be replaced by Russ Karel, while unit armourer Jack Wells also became very unwell. Elisabeth Sladen and Ian Marter approached Briant with concerns that he had forgotten to record a scene, only to then find themselves unable to locate it in their scripts.

Matters worsened on the 20th, the same day that several of the electricians disobeyed their instructions and interfered with the “Witch” rock formation. That afternoon, the motorboat being driven by Elisabeth Sladen on the pond in the “Witch's Parlour” cave went haywire, forcing her to jump overboard to avoid smashing into the cavern wall. Sladen nearly drowned before being pulled from the water by stuntman Terry Walsh, who subsequently fell ill. Soon thereafter, a ladder collapsed under an electrician, who suffered a broken leg. The final day saw visual effects assistant Tony Harding experience unusual difficulty in setting up basic pyrotechnics. Briant subsequently disposed of the arrowheads collected by his wife, and the rest of the production escaped the supernatural cloud that had dogged the Wookey Hole shoot.

As usual for a four-part Doctor Who story, Revenge Of The Cybermen was allocated a pair of two-day studio sessions, on Mondays and Tuesdays. As he had done on Death To The Daleks, however, Briant elected to use the first day exclusively for rehearsals and the second day only for recording, rather than the usual practice of rehearsing and then recording each scene in turn. Briant also favoured a set-by-set approach, rather than proceeding episode-by-episode.

As such, the first block was dedicated to material aboard the Nerva Beacon, with the cameras rolling on December 3rd in BBC Television Centre Studio 1. Briant was unable to complete the last two scenes, following Sarah's return to the Beacon in Episode Four, so this material was held over to the second block. Otherwise, all of the work on December 17th concentrated on sequences aboard the Cyberman spaceship and on Voga. The venue this time was TC3. It was subsequently decided to re-record the opening effects shot of the Doctor and his friends travelling via time ring. The remount took place during the making of Genesis Of The Daleks in TC8 on February 10th, 1975.

For the most part, Revenge Of The Cybermen followed the usual broadcast pattern for the latter part of Doctor Who's twelfth season, falling after Tom And Jerry and a news update, and before Dixon Of Dock Green. The lone exception was Episode Three on May 3rd, when Boss Cat (the title used in the UK for Top Cat) occupied the animation slot.

The following week, Episode Four brought Season Twelve to a premature end. Although Revenge Of The Cybermen had always been planned to be the year's fifth broadcast story, it was intended to be followed by Terror Of The Zygons. This was the final serial to be made as part of the twelfth recording block, and served as the conclusion of the narrative sequence begun in the season premiere, Robot. In January, however, the BBC decided that Doctor Who's thirteenth season should begin in the autumn -- for the first time since 1968 -- in order to get a jump on rival ITV's lavish new science-fiction drama, Space: 1999. Consequently, Terror Of The Zygons was held over to start Season Thirteen.

Gerry Davis was unhappy with what would turn out to be his final writing contribution to Doctor Who. Nonetheless, Revenge Of The Cybermen earned a peculiar distinction in the programme's history when, in 1983, it became the first Doctor Who story released on videocassette. The honour was more than a little dubious, however. Although touted as the choice of attendees at the Twenty Years Of A Time Lord event at Longleat House that April, Revenge Of The Cybermen was actually selected by BBC Video to take the place of the fans' real preference: Tomb Of The Cybermen which, at the time, was missing from the BBC Archives. Nonetheless, Revenge Of The Cybermen spearheaded a range which would grow to encompass more than 130 titles before coming to an end -- having essentially exhausted its supply of material and on the verge of being superseded by the DVD format -- twenty years later.

• Doctor Who Magazine #297, 15th November 2000, “Archive: Revenge Of The Cybermen” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who Magazine Special Edition #8, 1st September 2004, “You Ain't Seen Nothing Yet” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who: The Complete History #23, 2016, “Story 79: Revenge Of The Cybermen”, edited by Mark Wright, Hachette Partworks Ltd.
• Doctor Who: The Handbook: The Fourth Doctor by David J Howe, Mark Stammers and Stephen James Walker (1992), Virgin Publishing.
• Doctor Who: The Seventies by David J Howe, Mark Stammers and Stephen James Walker (1994), Virgin Publishing.
• In·Vision #5, June 1988, “Production” edited by Justin Richards and Peter Anghelides, Cybermark Services.