The episode begins with stock footage of a rocket launch, fancy electronic lettering, and then a hi-tech control centre. Even more than The War Machines this is positioned in real world technology, where space travel comes down to meticulous coordination and careful timing, and not the golden age SF futures of The Sensorites or The Ark. While that reflects the fact it was written by the show’s scientific advisor, Kit Pedler, it fits in perfectly with the new style brought in by Innes Lloyd and Gerry Davis.

That new style could be described as being ‘earthier’ than before: more ‘realistic’, and grubbier than the show used to be, and often located not at the heart of power, like The Reign of Terror or The Myth Makers, but in isolated, peripheral settings like the village in The Smugglers. This earthier style is clear in the design of Snowcap Base where the international (and totally male) crew have pin-ups on the wall, ogle at Polly, and use a lot more slang.

This episode feels particularly serious and urgent after four weeks of thigh-slapping adventures in the Seventeenth Century, with lots of grim-faced scientists earnestly discussing co-ordinates, General Cutler angrily dressing down the Doctor, Polly and Ben, and sweating astronauts trying to safely return to Earth in their rocket.

The script includes some genuine chills: the horrified astronaut Schultz declaring, ‘There’s something else out there’, and the Doctor grimly staring into the middle distance, warning Polly, ‘Pretty soon we shall be having visitors.’ He knows what is going to happen, is keen to not be around when the visitors turn up, and he’s only prevented from fleeing in the TARDIS by the permanently furious General. The arrival of the alien visitors themselves is great. After their spaceship lands silently, they’re first glimpsed as looming figures through the snow accompanied by the soon-to-be famous Cyberman theme (Space Adventure Part 2), before the episode ends with a close up of one of their blank, Edvard Munch faces.

This episode was broadcast on the same day as Hartnell was recording his final scenes for Episode 4. But the Doctor, Ben and Polly are almost superfluous to the story so far: impotent witnesses to events, ignored by the General, apparently unable to prevent what is going to happen, and only keen to escape the inevitable. This sort of powerlessness has previously been confined to the final episodes of the Season 3 historicals. To see it happen again here, in the first episode, and in the future, is very worrying indeed.

Next episode: The Tenth Planet – Episode 2