Most of the silly bits are knowingly ridiculous: the jokes about the embiggened Nucleus being another ranting megalomaniac, and the fact that – after repeatedly dismissing the idea the Doctor solves everything by blowing up Titan – are definitely deliberate. There’s an amusing bit of business when the Doctor opens a door on Titan and has to shut it again quick sharp because a man with a gun is standing right outside, and ‘I only hope he’s TARDIS trained’ is a funnier punchline than most of the “they all laugh at Spock” endings from Star Trek (a low bar, to be fair). Only the Nucleus claiming to be ‘mighty and invulnerable’ when it can barely move without assistance is obviously a gap between the imagination of the script and the budget-conscious logic of the production (CORRECTION: the script says the Nucleus is cumbersome and immobile, which instantly makes me like the story 10% more. Thanks to Revenge of the Swarm’s Jonathan Morris for pointing this out).

But the biggest issue with the serial is that – for all it has some big ideas – nothing really does them justice. I don’t just mean the production, which I’ve criticised at length (and to be fair, it’s the design of K9 that makes it work), but even the scriptwriting, which has some good concepts, and does nothing interesting with them. This ends as badly as any Hinchcliffe story, with none of the repartee, witty characterisation or lavishly ranting villains that made something like The Hand of Fear tolerable. I can barely believe Robert Holmes script edited this.

What’s left? Leela, at her dumbest, dressed up even more kinkily than usual in green PVC, like a wipe-clean Cathy Gale. Tom Baker having to deliver bland expository dialogue with just one mildly amusing joke (‘They appear to be hatching. Are congratulations in order?’). K9, running out of power at an inopportune moment, and making me wonder why the script makes such a thing about sending him to Titan. This is a story that has the Doctor turn evil – which The Invasion of Time does better, and a battle inside his brain – which The Deadly Assassin does better. But being generous, this is Graham Williams’ baptism of fire. You have to admire his intent, even if not everyone’s on the same page yet. I’d rather watch this than The Ice Warriors.

Next episode: Image of the Fendahl