‘If a frog with a funny head who can turn itself into a semblance of a human being in a matter of minutes, there isn’t much of a limit to what it can’t do. To say nothing of the dress-making.’ This is weird. For the sixth episode in a row, not a lot happens: vast swathes of it consist of people watching people – Monarch watching ‘the children’ Adric and Nyssa watching the crew of the spaceship; Persuasion watching the Doctor and Tegan watching the ‘recreationals’. Jeopardy is in short supply; the focus instead is on mystery – how can three billion life forms be on board one ship. Except even the mystery isn’t that taxing: when the crew don’t require oxygen and can be repaired, it’s not a huge leap to Bigon revealing he’s actually an android.

It’s not completely unlikeable, but the overall impression is Blue Peter in space, with Monarch providing a wry commentary on events: ‘Why does the old fool have to chatter,’ he complains of Bigon. Or, ‘We need doubt, it’s the greatest intellectual galvaniser’. Bits of the dialogue are quite fun and quotable (‘There’s time enough to get to Terminal Three and beat the Armada too’).

A lot of this episode was recorded in the second studio block, and Davison’s performance is a bit more confident than in the first episode (much of which was taped on his first day). He’s not quite settled into the role yet, and tends towards facetiousness rather than the sarcasm that becomes the hallmark of the fifth Doctor’s humour. Again, this is due to the script, with some of the funnier lines sounding like they were written for Baker (calling Persuasion ‘Percy’). Still, it’s nice to see him given something assertive to do, even if that involves patronising an unusually weepy Tegan: ‘Come on, and try to keep calm. We’ll get nowhere if you lose your head.’

Next episode: Four to Doomsday – Part Three