‘I am prepared for the worst.’ From Logopolis ‘the unravelling will spread out until the whole universe is reduced to nothing’. It’s a grand idea, and Bidmead makes it accessible by showing the localised effects – the great city falling silent, its people turned to dust and its streets collapsing on themselves. The eerie silence and accelerating decay contain hints of the Daleks’ time destructor on Kembel. The scale of the fourth Doctor’s last hurrah is epic.

So why is so much of this prosaic? The Master creeping round shrinking people as he chuckles, and then wheeling a couple of noise-cancelling speakers about the place can’t match up to the grandeur of Bidmead’s ideas. And there are already too many companions: both Nyssa and Tegan have to confront the fact of their loved ones’ deaths here: Tegan at least gets a crumb of comfort from the Doctor (‘I’m so sorry, Tegan’). Nyssa doesn’t even get that (more significance is given to her arm-controlling bracelet than the notion of the Master possessing her father’s corpse). The new series straddles the line between cosmic disaster and personal tragedy more adeptly.

Fortunately, Baker is carrying this, and it’s an astonishing performance, full of anger and odd flashes of humour (his broad smile when the Master realises the terrible depth of his mistake). I’m not sold on his final, slightly brutal rounding on his young companions, but Baker plays it almost as if he’s being cruel to be kind*, to force them to abandon him and join the Watcher in the TARDIS, while he collaborates with the Master to save the universe in another excellent cliffhanger.

We also get to meet Ainley’s Master. His wolfish tilt of the head as he lurks in the shadows of a Logopolitan cave to greet Nyssa is creepy, and he generally seems crueller than before, enjoying torturing the young companions, taunting Nyssa about the usefulness of Tremas’ body, and killing for fun. His plan to learn and perhaps appropriate the secret of Logopolis isn’t out of keeping with his predecessor’s grandiose villainy, but he’s also insane in a way the Delgado version never really seemed to be. What he isn’t is the Watcher, who the Doctor now describes as ‘my friend in there’, and who brought Nyssa to Logopolis. Wandering through the background of shots like Pipes in Ghostwatch, he’s being set up as the final mystery of the Tom Baker years.

Next episode: Logopolis – Part Four

*I’m indebted to Jonathan Morris for sharing the script for this scene. It shows that Tom is playing it as scripted by Bidmead – ‘deliberately making the coming separation easier for his companions’