The colour recovery process, while miraculous, works better on some episodes than others. This one has a slightly nicotine-stained patina which actually suits the seedy nature of the the villains introduced here (disposing of bodies in a gravel pit), with grey grass and a washed-out sky giving a properly wintry feel to the location filming.

The resolution to the cliffhanger is properly Quatermass: the space capsule is empty. The astronauts have already been removed. To try to put the Doctor and UNIT off the scent, Sir James and General Carrington – one of last week’s villains now revealed as a top brass military man – concoct a cover story about mysterious contagious radiation. It’s the first time the show has really played the conspiracy angle so straight, and it works really well. The Doctor’s refusal to take anything at face value means Carrington has to take him to the secret facility where the astronauts are being held – and presumably, given his laid back reaction to finding they’ve been kidnapped, organising their transfer to another location. The idea of the Doctor and Brigadier going up against the British Establishment is great, and it’s helped by a script that consciously holds back half the story – to the extent that we hear Cornish, Reegan, Sir James and the Brigadier all having one-sided phone conversations – so we’re left second guessing what’s really going on.

It at least seems clear that the Doctor is right when he says, ‘I don’t know what came down in Recovery 7 but it certainly wasn’t human.’ The mysterious astronauts are a great image – towering impassively over Cyril Shaps in his trademark role of twitchy boffin, and reaching out gloved hands towards their victims.

Probably my favourite bit of the episode is its ending: Liz takes Bessie as she is lured into a trap. Caroline John seems to relish the chance for some proper action after being pretty sidelined as a test-tube carrier in the last story. This week she gets to do a car chase, run dramatically across a weir in a massive hat, and whack a man over the edge, all accompanied by Dudley Simpson’s music which sounds exactly like the theme to an ITC adventure show: The Shaw Thing. Awesome.

Next episode: The Ambassadors of Death – Episode 4