‘No Keeper lasts forever, and the period of transition is always difficult.’ As the show hurtles towards the departure of its leading man, this could almost be a metaphor for the uncertainty surrounding its future. I’m sure this must have partly inspired some of The Keeper of Traken: lines like the defiant, ‘Trakens have survived times like this in the past. We shall do so now’ put a brave face on what must have been a deeply unsettling time behind the scenes.

Like Warriors’ Gate, this has an almost fairytale quality to it; set in a sort of Shakespearean Arden, a realm where everyone is very good to one another, and evil is turned to stone just by the virtuousness of the atmosphere. But something is rotten in the state of Traken: the old Keeper senses it, and in a beautiful sequence sketches in the past and present of the planet as lyrically (if more sedately) as Biroc did in the previous story. The scenes in the TARDIS are delightful, with Baker seeming to actually notice Waterhouse’s presence for the first time, and Adric actually looking like a proper companion rather than the slightly awkward add-on he’s been in the E-Space episodes. This tends to hide the fact that this is another Season 18 serial where the Doctor doesn’t actually get to investigate and discover the environment he’s arrived in, but learns about it after the audience has, and doesn’t even arrive until five minutes before the end. It’s a very long way from the spirit of exploration of the 1960s, or even the Doctor being the one who explains to his companion, as was the case through a lot of the 1970s.

Instead, we get some scenes of the lavishly-dressed Trakenites declaiming to each other in cod-Shakespearean dialogue. It works very well here, because it suits the otherworldly, fairytale nature of Traken: it’s going to work less well in future when everyone in the universe, including American teenagers, talks like this. But The Keeper of Traken can’t be blamed for that. Again, there’s the hint of conflict between Kassia’s superstition and Tremas’s science, and the notion that their personal union has cosmic ramifications rather like Anakin and Padme’s marriage in Star Wars.

I think this is beautifully done: stagey, but again that suits the material. I love the Doctor’s confident arrival, at the invite of the Keeper, oblivious to the true nature of the evil waiting for him. Even Adric senses it. The cliffhanger, as that evil invades the heart of Traken, and the agonised Keeper seems to denounce the Doctor, is wonderful – even if the Melkur peeping from behind a curtain is also slightly comical. After a very shaky start, this season is turning into something special.

Next episode: The Keeper of Traken – Part Two