Landmarks No.29

The Five Doctors.
The second big anniversary story, marking the 20th Anniversary.
Another multi-Doctor tale, and one which allowed for appearances by a number of companions and monsters.
The easiest way of bringing different Doctors together was to have the Time Lords involved in some way - and this lead to the return of Borusa (played by yet another actor) as well as the Master.
Originally intended to be scripted by Robert Holmes, the story was written by Terrance Dicks - his only real commission in the JNT era. JNT was very reluctant to bring back any of the older writers, and Eric Saward had had to fight to get Holmes back on the show. Dicks' last story (State of Decay) had only been made because there was a dearth of scripts at the time and this was already on the shelf and good to go, with very little needing to be done to it.
Holmes would have included a fake Doctor - the First - making a feature of the fact that the part had to be recast (Richard Hurndall taking Hartnell's place).
A clip of Hartnell from The Dalek Invasion of Earth is seen at the start - a nice touch but one that reinforces he's being "copied" by someone else for the rest of the drama.
Tom Baker played the hokey-cokey for a while (in, out, in, out etc), before deciding against returning. Material from the unfinished Shada enabled him to be included.
The Doctor-Companion pairings had to be changed about when Tom withdrew. Troughton was to have been paired with Jamie - but Frazer Hines could not get time off from Emmerdale Farm. Sarah would have been paired with Tom, but she moved to Jon Pertwee, and the Brigadier moved from Pertwee to Troughton.
Hines was able to attend for one day, so appeared in a cameo as one of the Tower's "ghosts" - alongside Liz, Yates, and Zoe.
K9 appears briefly with Sarah - "canonising" K9 & Company.
Returning monsters included a Dalek (in what is little more than another cameo), Cybermen and a Yeti. (Pertwee was originally supposed to have encountered Autons instead of Cybermen, in a high street mock-up which was part of The Game of Rassilon).
As such, this marks the Third Doctor's only meeting with the Cybermen.
A fair bit of new Time Lord mythology is unveiled - mainly revolving around the Dark Times of Rassilon's era.
Is Rassilon dead? The body is lying there but he appears as an image which can interact with those around him. He will be resurrected by the Time Lords to lead them in the Last Great Time War.
The regeneration limit can be exceeded, as the Master is offered a whole new regenerative cycle should he help save the Doctor.
Immortality is also possible - though in the form of perpetual imprisonment. That's how Rassilon chooses to use it, but can it be given in other, more benign, ways?
Other items of significance include the duration of the episode - the longest ever - and the fact that this was the first time a story had debuted outside the UK. The US saw it on the 23rd November 1983 but the British transmission was held back so that it could form part of the BBC's Children In Need telethon.
The novelisation of this story actually hit the shops prior to transmission.