OVERALL EPISODE NUMBER: 560
STORY NUMBER: 117
TRANSMITTED: Monday 04 January 1982
WRITER: Christopher H. Bidmead
DIRECTOR: Fiona Cumming
SCRIPT EDITOR: Eric Saward
PRODUCER: John Nathan-Turner
RATINGS: 10.1 million viewers
FORMAT: DVD: Doctor Who - New Beginnings (The Keeper of Traken/Logopolis/Castrovalva)
While escaping with the newly regenerated & confused Doctor, Adric is captured by security guards and only freed by the arrival of the Master's Tardis. Adric sets the Doctor's Tardis in flight, following him into the depths of the vessel where the Doctor is seeking the Zero room to rest & recuperate in. He finds the Doctor, but vanishes. Nyssa & Tegan guide the Doctor to the Zero Room where he regains some strength but on her way back to the console room Nyssa notices the Tardis is getting hotter. Tegan sees an image of a captive Adric warning them of the Master's trap. Nyssa discovers the Tardis has been set on a course for the hydrogen inrush: event one: the Tardis is heading for destruction in the biggest explosion in history.
Welcome to the start of the Fifth Doctor's adventures. The episode follows the pattern set by Spearhead from Space & Robot by showing the Doctor somewhat confused but places him in a familiar setting (then UNIT, here in the Tardis with his companions) to reassure the viewers. The episode rolls along nicely from "can the Doctor & his companions escape the security guards" through "can the Doctor find the Zero Room" to "why is the Tardis getting hotter and where is it going?". It doesn't allow a lot of time to stop & think but symbolically shows that this is something a little different by shedding the fourth Doctor's clothes and unravelling his trademark scarf.
The new Doctor Who is played by the then thirty year old Peter Davison, at that point the youngest actor to play the Doctor. He'd come to fame playing vet Tristan Farnham in All Creatures Great & Small, which producer John Nathan-Turner had worked on, and when the time came to recast the role of the Doctor Nathan-Turner remembered him. Nathan-Turner had a photo of Davison at a charity cricket match on his office wall and this provided the inspiration for the Doctor's costume.
Location filming for this episode took place at Crowborough Wireless station, a different location for the Pharos Project to the one used in Logopolis. This was so all the location work could be done in one locality and was dictated by the major location used in the next few episodes. Playing the head of security at the project is Dallas Cavell who had previously been in several Doctor Who stories: he was the Road Works Overseer in The Reign of Terror, Bors in The Daleks' Master Plan, Trask in The Highlanders and James Quinlan in The Ambassadors of Death. Meanwhile one of his security guards, the one seen manhandling Nyssa & Tegan, is a last Doctor Who role, uncredited as usual, for Harry 'aitch Fielder. His complete list of Doctor Who credits prior to this episode, stretching back to 1967, is The Enemy of the World: Central European Guard (uncredited), The Wheel in Space: Wheel Crewmember (uncredited), Planet of the Spiders: Guard (uncredited), Revenge of the Cybermen: Vogan (uncredited), The Seeds of Doom: Guard (uncredited in Part 3 but credited in Part 4), The Deadly Assassin: Guard (uncredited), The Face of Evil: Second Assassin (uncredited), The Invisible Enemy: Titan Base Crewman (uncredited), The Ribos Operation: Levithian Guard (uncredited), The Armageddon Factor: Guard, Shada: Krarg & Meglos: Tigellan (uncredited). The day after this episode aired he made his first appearance as the security guard on Thames Television's CBTV a job that would occupy him for the next few years and get his face known with many children of my age. There's a selection of clips on Harry's You Tube Channel. His website details his long career as a "supporting artist" in films & television and he's in the process of writing a book.