At this stage, producer Barry Letts and script editor Terrance Dicks have every reason to be pleased with themselves. They’ve turned a show that by all accounts seemed to be on the brink of cancellation between 1969-71 into a success story about to go into its tenth series; they’ve weathered the storytelling challenges of the previous producer’s decision to strand the Doctor on Earth, and they’ve created a team of regulars and an aesthetic for the show that’s added two million onto the viewing figures, pushing it back towards its mid-1960s heyday. In this imperial phase, surely they’re entitled to enjoy themselves.

The beginning of The Time Monster reminds me of a later imperial phase: a dream sequence of the Master laughing evilly amid ominous warnings of doom is pretty much exactly how The End of Time begins in 2009. The erupting volcanoes also feel like a call-back to the Mind Parasite’s attacks in The Mind of Evil, although there it was the Doctor looming over the Master and laughing. UNIT is once again hunting for the Master. Which also means we get to see the UNIT Fam for the first time in four months. And they’re not quite as they were. Benton is as put-upon and stolid as ever, to be fair, but both the Brigadier and Yates have been letting their hair grow, and Nick Courtney and Richard Franklin are playing them as fun guest star turns rather than as series regulars.

In this, they’re only responding to the script. Robert Sloman’s previous co-write, The Dæmons, showed the Fam with their hair down. This goes further, having the Brigadier seem to be a bit of a buffoon (‘That’s a fearsome looking load of electronic nonsense you’ve got together, Dr Ingram? How does it all work? In words of one syllable’), cancelling Benton’s leave on a whim, and cracking jokes about the Doctor consulting the entrails of a sheep. I love Nick Courtney, but this is not the same Brigadier who was running a top-secret paramilitary organisation in Season Seven, or even organising a world peace conference 16 episodes ago.

The whole script, though, has an archness to it that encourages arch performances: the scenes between Wanda Moore and Ian Collier are excruciating, with wry dialogue (‘May God bless the good ship Women’s Lib!’) accompanied by some teeth-grindingly whimsical music from Dudley Simpson (elsewhere, Simpson adds a jaunty comic theme to the scenes of the Doctor and Jo using Bessie’s Super Drive). Some of the actors respond to this better than others: while equally OTT, John Wyse’s brilliantly cantankerous performance (‘What, pray, is “interstitial time”?’) is a highlight. Delgado and Manning are good enough to stick to their guns, and deliver entirely consistent performances (Delgado also gets the best line, claiming to be ‘A lifelong pacifist’ to avoid having to meet the Brigadier in person). And Jon Pertwee, who looks like he’s wandered off the set of Whodunnit?, makes the interesting choice to play against the script, making the Doctor almost as distracted and cranky as he was during Season Eight.

I like some of this: the living dreams of visions and mystic crystal revelations are so of their time they’re almost timeless, and it’s a pleasure to see Delgado back. But I could have done without this feeling quite as self-indulgent, or the cliffhanger of the Master apparently going mad in the middle of an experiment.

Next episode: The Time Monster – Episode Two