The first few minutes of the episode feel like a proper Troughton comeback, as he takes centre stage to battle the anti-mater blobs at UNIT HQ. It’s a lovely showcase of his character, as he pokes at the creature then runs back into the TARDIS when it reacts. He forms a surprisingly effective double act with John Levene, with Benton clearly taking on the unavailable Frazer Hines’ role (you can practically hear Jamie saying the lines when the Doctor leaves Benton in charge of an electronic gizmo). Later, when the Brigadier is stubbornly refusing to take him at his word, there’s a flash of his old wolfish grin, and a sort of pained exasperation (and later, outrage when the Brigadier presents him as the third Doctor’s assistant). And he gets another great scene where he apparently wrecks the Brigadier’s radio before cleverly turning it into a better version, like the scatty genius of The Krotons. He doesn’t play this exactly like he did in the 1960s, acting a lot of scenes with a vaguely amused superiority that, possibly, suggests that he knows he can’t actually be too badly hurt because he has to live to be the third Doctor, but this is probably the episode that gives us the best idea of what a Season Seven Troughton might have looked like.

Elsewhere, the third Doctor and Jo have been transported to a barren wilderness (head canon: it’s Omega’s recreation of the outer wastes of Gallifrey), but the Doctor seems quite invigorated by it. Pertwee’s rarely been quite so laid back as he is in his first scene here, reassuring Jo that they aren’t actually in some kind of afterlife (Jo made a similar assumption about going to heaven in The Time Monster – she’s very confident she’s going to end up in the Good Place). Pertwee gets to show of some stage magic, before referring to their mysterious kidnapper as a ‘great intelligence’ (probably just a coincidence, although there’s nothing to say the formless, shapeless Intelligence couldn’t have been Omega trying to regain access to our universe by taking over the Doctor – after all, it’s what he tries next time we meet him).

Elsewhere, we get our first proper glimpse of the politicking that will characterise all Gallifrey stories from now on, and of the masked villain, who looks like something out of Greek theatre wearing the same sparkly robes as the Time Lords. The only person who doesn’t come out of this well is the Brigadier, as the alarming character changes initiated in The Time Monster continue and he stubbornly and incredibly refuses to take the Doctor at his word, before claiming that the TARDIS has been built with UNIT funds. When even Benton comments, ‘I think the strain’s been a bit too much for him’ it’s pretty obvious that the Brig’s not quite right, although the compensate Courtney, he gets the episode’s best line: ‘as long as he does the job he can wear what face he likes.’

Next episode: The Three Doctors – Episode Three