The last episode sees the villains spinning in increasingly erratic orbits around the Doctor’s centre of gravity, as he takes over their base and uses their weapons against them, apparently at the cost of his own life. This means Azaxyr gets a showdown with the Pels and is ultimately stabbed by a miner as he threatens to kill their Queen. It’s a slightly ignominious end, but there’s some nice theatre as his corpse is borne away. The venal Eckersley gets a less noble end: hunted down by Aggedor, in its role as Hound of the Baskervilles to his Stapleton, and mauled to death. It’s just desserts for the man who appropriated the image of Aggedor to line his own pockets.

But the most interesting piece in the final episode is the apparent death of the Doctor. Pertwee’s quitting of the series was announced in February 1974, so the audience has had a couple of months to digest the idea, and this episode really leans into it. For a huge chunk, Sarah thinks the Doctor has actually died. There’s a scene of her, disconsolate, in the communications room, head resting on a desk. She wanders, hopelessly, through the tunnels to the refinery to find the Doctor’s body, and weeps over it – and wakes him up. ‘Tears?’ he asks, just like he’s going to do in six episodes’ time. How much of this is foreshadowing, how much teasing the audience that maybe this is the promised end I’m not sure, but just as Letts and Dicks went to some lengths to set up Jo’s departure, so they’re definitely doing a ‘Your song is ending’ set-up for the third Doctor.

The rest of the episode confirms that the back half of the serial is much better than the front. Thalira’s queenly indifference to the Ice Warriors is better than her emoting, though her furious ‘Look what you’ve done’ to Eckersley as they pick their way through Pel and Martian corpses is her first moment of conviction all story. Overall, I think this achieves a basic level of competence and drama above The Time Monster, but it’s awfully thin stuff. Rehashing The Curse of Peladon without any new ideas, and re-using Lennie Mayne rather than giving it to a director like Michael E Briant who might have been able to do something to spice it up, feels like an admission of defeat, a desire to just get it done rather than anything more ambitious. In that respect, this suggests that the long-term production team are as checked out as Pertwee apparently was by this stage. The “era” is running on fumes.

Next episode: Planet of the Spiders