Sad to say, like several Season 13 stories, this final episode doesn’t entirely work. In the last scenes the Doctor apparently allows half the masked revellers to be murdered by the Brethren, and then allows the Brethren themselves to be vaporised while he imitates Hieronymus (including a Dead Ringers style impersonation – sign him up, Big Finish). It’s ruthless, and a bit of a Pyrrhic victory given how important the gathered dignitaries (‘The most precious heads in all Europe,’ says Marco, gazing adoringly at the Duke) are meant to be to Earth’s future.

The explanation is very vague: presumably the Doctor drains Mandragora’s negative-charged high energy particles leaving a fairly harmless residual spark behind. Perhaps, therefore, the massacre at the masque isn’t as fatal as it appears (although the dusting of the Brethren doesn’t really do anything to suggest it wasn’t). ‘A case of energy squared’ is the best we get. I’m beginning to think Robert Holmes wasn’t actually very good at endings.

In mitigation, we get the lushest scenes of a lush story. While the denouement is botched, the climax is brilliant. The masque is appropriately gorgeous (if slightly underpopulated). The Masque of the Red Death inspiration becomes clear when cowled figures move sinisterly into place around the edges of the room and the screen is drenched in red light as the partygoers are struck down.

We also get a very witty script, performed by Baker and Sladen at the top of their game. Their friendly squabble as they walk the corridors of the palace is a brilliant way of getting the exposition out of the way in an interesting way. The Doctor’s introverted brooding contrasts with Sarah’s extroverted, journalistic interrogation. Until he’s worked it out in his own mind and he’s suddenly expounding on the scale of Mandragora’s horror: ‘It takes away from man the only thing worth having… A sense of purpose… The ability granted to every intelligent species to shape its own destiny… It’ll turn you into sheep. Idle, mindless, useless sheep.’ And one of my absolute favourite Doctor and Sarah exchanges:

SARAH JANE: You know, the worse the situation, the worse your jokes get… Things are bad, aren’t they?
THE DOCTOR: Yes.
SARAH JANE: Very bad?
THE DOCTOR: Desperately bad, but we can only do our best and hope.

In general, Baker seems to be delighted with this. ‘I love a knees up,’ he grins when he hears about the masque, and takes time out to pick an elaborate lion mask (and fool around roaring at Sarah Jane). And this enthusiasm has infected me: this one has gone up in my estimation more than any other Tom Baker story so far. It’s perfectly designed to look amazing on a BBC budget: no rubber monsters or giant puppets, just a few well chosen effects (the glowing sphere under Hieronymus’ cowl; the frazzled blue corpses). I can see why Philip Hinchcliffe picked this one for The Five Faces of Doctor Who in 1981. Everything about it bar the last couple of scenes is great.

Next episode: The Hand of Fear