Kit Pedler clearly took a leaf out of Terry Nation’s book when he wrote The Moonbase: so much of it is repurposed from the earlier Cyberman story, including both the broad plot beats, like the base under siege, but also in specific details – like the Earth rocket the Cybermen deflect into the Sun in both serials.

The use of the Gravitron to defeat the Cybermen is hardly a shock – it was heavily implied in the last episode – but it’s a satisfactory turning of the tables on the monsters, and an opportunity for the Doctor to demonstrate his ingenuity where in The Tenth Planet the final episode was essentially waiting round for Mondas to explode and the Cybermen (and the old Doctor) to die.

In nearly every respect, The Moonbase is the superior serial. The Cybermen vanished from The Tenth Planet 3, and when they turned up again they were very easily dispatched, whereas here their reintroduction is a masterclass in how to do it well – a shadow, a glimpse of detail, the reveal of a single specimen at the end of the first episode, and the reveal of the true scale of the threat at the end of the third. Having blown it too soon, The Tenth Planet had to come up with the Z-Bomb plot to create an element of second-half tension, but here the steady claustrophobia, the moments of “the call’s coming from inside the house” horror as people realise the monsters are in the room with them, and Hobson’s increasing desperation, are a more natural and compelling progression.

Most importantly, while The Tenth Planet failed to provide anyone but Ben with much of role, all four regulars get something to do in this: even Jamie, now recovered and wearing a new kilt (presumably from the Moonbase stores, as he was wearing a space suit when he arrived). Best of all, the Doctor has been clearly repositioned as the hero of his own show again, after a few weeks when he felt like the zany guest star. The wolfish smile Troughton gives as he contemplates the Cybermen’s weak point; the way he stands resolute while the rest of the crew cower from the Cyber-laser attack (and then staggers a bit afterwards, like he wasn’t quite as confident as he made out); taking control of the final defences, showing while everyone else has been reacting to the latest danger he’s been planning ahead. All of the pieces of his characterisation are now in place, and this is magnificent.

Similarly, the TARDIS crew slipping away before they’re asked help to clean up the mess is now clearly going to be an ongoing joke – as is the happy tag scene inside the TARDIS, with a cliffhanger that links directly into the next adventure…

Next episode: The Macra Terror