This episode contains what’s pretty much the second Doctor’s mission statement:

THE DOCTOR: There is something evil here and we must stay… There are some corners of the universe which have bred the most terrible things. Things which act against everything that we believe in. They must be fought.

While latterly the first Doctor stayed and helped because it was the right thing to do, and he couldn’t abide injustice, he was principally ‘a citizen of the universe and a gentleman to boot’ exploring a universe of wonders. The second Doctor is a pensive traveller through a universe of terrors. From being an unguessable, even alarming figure 12 weeks ago, he’s now become a much more reassuring character – probably a necessary sacrifice of unpredictable whimsy in favour of something more palatable to most of the audience.

Again, for a sixth successive week, Troughton is the only regular to get anything worthwhile to do (Polly screams at the Cybermen and makes some coffee, Jamie mutters deliriously, Ben hovers). And yet again, he’s the only thing that makes this episode worthwhile. Just as in The Tenth Planet, Pedler is easily diverted into long technical chat between the base crew: there’s an interminable scene about checking the Gravitron, which is only lifted by the arrival of the Doctor collecting samples from the clothes of the scientists as they stand round gassing.

Later, he pretends to have made a breakthrough just to get Hobson off his back and buy some time. And when he actually does work out what’s happening there are a couple of great moments – knocking Hobson’s sugary coffee from the commander’s hands, and then deducing where the Cybermen may be hiding inside the base.

Nothing in the rest of the production comes close, although there is a moment of genuine horror as two of the base crew are brutally clubbed down and presumably removed for Cyber-conversion, leaving their empty space suits lying in the lunar dust. The new Cybermen are also quite impressive – picking up the infected crewmembers and carrying them under one arm, and looming, mute and impassive with none of the sing-song chattiness of the old versions. However, the cliffhanger involves one of them hiding under the bedclothes like its Mondassian predecessors hid inside anoraks. It’s equally absurd.

Next episode: The Moonbase – Episode 3