A lot of the effects look like something from Top of the Pops or an early 1980s pop video – like the Doctor hanging from the lighthouse window, or Reuben the Rutan’s transformation. It’s obviously a long transition period, but for the first time I feel like this is starting to look like the show I remember from my own childhood in the 1980s. The Rutan itself looks like a lump of phlegm, but speaks with a fairly clipped, RP accent – much like Linx the Sontaran. And like the Sontarans, the Rutans of Ruta 3 are ruthless warmongers, concerned only about victory at any cost. No wonder the Doctor’s never taken sides in their war.

Famously, this is one of the few stories where – just this once – everybody dies. Adelaide gets the kind of casual death she deserves – she’s been an extraneous appendage (there’s a lovely scene where she faints and Leela rolls her eyes), so it’s fitting she gets killed by one. Equally fittingly, Skinsale is ‘dead with honour’, but a victim of his own greed – had he not been scrabbling in the dirt for Palmerdale’s diamonds he’d have escaped the advancing Rutan. Dicks avoids this looking like a complete failure for the Doctor, though, by an eleventh hour raising of the stakes to include the whole planet Earth: the Rutan has succeeded in contacting its fleet, a warship is rapidly approaching, and it’s the Doctor’s quick thinking (inspired by Leela’s suggestion) that prevents global disaster. This is like a more satisfying version of the end of The Sontaran Experiment (where the destruction of Styre and his report averts an invasion).

I’ve really enjoyed the single-mindedness of this serial. It’s much more contained and disciplined than most of Robert Holmes’ scripts. The result is less barnstorming; it’s hard to imagine any of the characters in this (had they survived) spinning off like Jago and Litefoot. I don’t envisage the audio adventures of Skinsale and Palmerdale. And Dicks is expanding on world-building ideas introduced by Holmes in The Time Warrior rather than coming up with his own alien species and backstory. On the other hand, this is a much more focused piece of work, brilliantly structured to continuously escalate the peril at the same time as it narrows down the pool of characters – the script equivalent of the Hitchcock Vertigo shot. It’s also much more repeatable than something like The Talons of Weng-Chiang: conceived to be achievable, well on a BBC budget.

The Doctor is also suddenly closer to the dangerously unsettling version of Season 12. He seems genuinely troubled by these events, and there’s a moment near the start of this episode where Baker makes the Doctor seem very tired, as he struggles to live up to Leela’s expectations of his Time Lord power. Later, the Doctor’s reaction to Leela’s gloating over the mortally wounded the Rutan is perfect, and:

DOCTOR: Been celebrating, have you?
LEELA: It is fitting to celebrate the death of an enemy.
DOCTOR: Not in my opinion. I haven’t got time to discuss morality.

But a few minutes later, he’s advancing on Leela, eyes twinkling and reciting The Ballad of Flannan Isle, I was strongly reminded of the moment he approaches Harry with a skipping rope in Robot, reciting ‘Send for the Doctor quick, quick, quick’. I’ve enjoyed Baker’s evolving performance a great deal, but this, sombre with flashes of wit and genius, feels as back to basics as the story as a whole.

Next episode: The Invisible Enemy