It’s 1969, the year of the Moon landing, so naturally this episode focuses on the process of actually getting there. It’s not exactly realistic – but there’s more focus on the dangers and technical difficulties of space travel than in any story since The Tenth Planet. No tea-trays shoring up pressure dome punctures here. Instead, a rocket launch complete with mission control countdown; the effects of G-force, and the importance of radio communication and telemetry. Arguably this just slows down the story, but I’m sure in 1969 it gave it a real contemporary buzz.

Plus, while the script takes its time over the details, Michael Ferguson keeps things interesting with some of the flashiest direction so far. He shoots through girders, and includes loads of camera movement. The discussions in the space museum aren’t just a strong of cuts between talking heads, but a roving camera follows the actors around the set as they talk, injecting some dynamism into the talky scenes. Elsewhere he has Fewsham sitting, lonely and gaunt, looking small in the centre of a wide shot of the moonbase set, waiting to carry out his cowardly betrayal of humankind. And the scene where Phipps kills an Ice Warrior in a flare of negative and disorienting angles is brilliant.

Terrance Dicks is also working his magic as script editor. Assuming Brian Hayles hadn’t magically become a much better writer in the year since The Ice Warriors, the stronger characterisation in the dialogue is most likely a result of Dicks’ influence. Fewsham is a feckless wet blanket of a man, and Terry Scully is a great piece of casting – looking and sounding like one of Richard O’Callaghan’s hapless Carry On… characters. Miss Kelly is a bit of a cliché – the brainbox woman who lacks warmth and “femininity”, but who nevertheless is the last hope of the human species. And Radnor, while very much in the spirit of all those Troughton base commanders, seems a bit less like a grumpy cipher and more like a real person.

Only Slaar isn’t obviously an improvement over The Ice Warriors. His costume enables a much more viable range of performance than Varga’s, and Bennion’s performance is great. But there was something about Varga’s gleefully sadistic cruelty that made him a genuinely nasty villain, whereas Slaar seems more like a competent military commander. On balance, though, this is already about a billion times better than the Martians’ first appearance.

Next episode: The Seeds of Death – Episode Three