After an episode of minimalism, this suddenly floods the screen with a string of bizarre and unsettling images: Jamie transformed into a cardboard stand-up and then a swapped head (the Master of the Land of Fiction clearly has one eye on the merch opportunities). Zoe is trapped behind a door painted on a wall that becomes a jar. There are clockwork soldiers, redcoats, a forest of letters, creepy children and a unicorn.

At the moment, none of it really needs to make much sense. The idea is to wrong-foot the audience – and as long as we can see the Doctor is as baffled by it all as we are (although he seems to be piecing something together), we go with it. Troughton does a superb job navigating through the oddness, pivoting between cautious and watchful, cocky – when he thinks he’s solved a puzzle, and back again (‘Oh no I’ve done it wrong!’ he wails as Jamie is restored with a new face). His performance is the glue that holds it all together – which is no mean ask, given these episodes were made at the tail end of a 46-week run.

Writer Peter Ling immediately establishes the peril of the situation: Jamie is shot by a redcoat and Zoe plummets into a dark pit within seconds of their arrival, and the Doctor is held at both gunpoint and sword-point by the inhabitants of this strange world. For all the lack of logic, this doesn’t feel like light whimsy. It’s very much in the spirit of 1968: the colourful Magical Mystery Tour Victoriana of 1967 tinged with something more sinister and dangerous: words used as weapons.

Behind it all is the mysterious ‘Master’. We can ret-con the Doctor’s wry reaction to this revelation as him suspecting his old frenemy is somehow involved, but at the time anyone who remembered 1966’s The Celestial Toymaker might have got a hint of Michael Gough’s Toymaker. After all, the Master sits in the centre, watching his games on TV screens, and suddenly switching to a harsh intonation whenever he’s issuing orders – just like the Toymaker did. And it’s a curious coincidence that Jamie gets his face changed by the Master’s magic in almost exactly the way Wiles and Tosh were going to use the Toymaker’s power to write out Hartnell in 1966.

Next episode: The Mind Robber – Episode 3