Cybermen (1975), as producer John Nathan-Turner wanted to bring back an old enemy, but resisted using the Daleks. Before the title was changed to Earthshock, Nathan-Turner was adamant about keeping the return of the Cybermen a secret. He instructed Eric Saward not to have any reference to the Cybermen in the story's title. Nathan-Turner even had the studio observation galleries closed for the duration of recording and turned down an offer from Radio Times to provide advance publicity of the Cybermen on their cover. The success of this convinced Nathan-Turner to continue to mine the series' past continuity for ideas and old enemies. After the success of using archive footage for the flashback sequence in Logopolis (1981), Producer John Nathan-Turner consulted with series continuity adviser Ian Levine and asked him to prepare another such montage for this story. Levine selected one clip from all of the previous Doctors, save for Jon Pertwee who never had a Cyberman story (though they had been briefly glimpsed in two serials from his era). Levine's selected clips were: the First Doctor from episode 2 of The Tenth Planet (1966), the Second Doctor from episode 6 of The Wheel in Space (1968) (with dialogue from the Earthshock Cyber Leader referring to The Tomb of the Cybermen (1967), at that time missing from the BBC archives) and the Fourth Doctor from part 3 of Revenge Of The Cybermen (1975). All the clips were presented in monochrome to preserve continuity, as the first two extracts were originally recorded in black and white. The exterior sequences seen in the first episode were shot on Thursday 29 October 1981 at Springwell Lock Quarry, near Rickmansworth, Hertfordshire. The Cyberscope prop was built using parts the modelmaker (Martin Bower) had scavenged from the Nostromo set constructed for Ridley Scott's science fiction film Alien (1979). Similarly, the digital readouts on the device flash up a random series of numbers, which were also seen on the monitors of the Nostromo set. Earthshock was Peter Grimwade's last work as a director on Doctor Who. According to an interview with Eric Saward in 1986, Nathan-Turner subsequently fell out with Grimwade and refused to use him again, which was a source of tensions between Nathan-Turner and Saward. Although this was his last job on Doctor Who as director, he would write three serials for the Davison era; Time-Flight (which follows on from Earthshock), Mawdryn Undead and