‘Now I’m vexed.’ I like that Aaronovitch writes this as a proper “The Two Brigadiers” with the same slight tension and mild sniping between Lethbridge-Stewart and Bambera as we’d get between two incarnations of the Doctor. They even get a memorable first meeting: ‘I am the Brigadier,’ snaps Bambera. ‘So am I,’ announces Lethbridge-Stewart as he emerges from Arthur’s spaceship with the rescued Doctor. Rightly, though, there’s no implication that the old Brig is the better version and barring a couple of snide remarks (‘I thought you’d retired’; ‘Good lord, is that her name?’) the two of them are quickly on the same page. This era of the show likes the popular history of Doctor Who but is confident enough to suggest we’ve never had it so good. Bessie might be back, but the number plate is very clearly Who 7.

This is the best episode of a serial that’s overcoming its shaky start to offer up some striking images, like Ace emerging as the Lady of the Lake clutching Excalibur and immediately offloading it; Morgaine confronting Lavel before restoring Elizabeth’s sight, and The Devil Rides Out homage of the last few minutes (complete with vintage car). The dialogue includes some good one-liners (‘That’s what I said Shakespeare’), and some slightly clunky but sweet kisses to the past (‘we’ve even got gold-tipped bullets for you know what’), and some even clunkier Ace character work. My sense is that this is about a hundred times better than what we’d have got had they tried it for Season 21.

It’s almost a hangover from Season 25, and an attempt to keep the anniversary party of the previous year going (except most of the guests have gone home and the lights have been turned on) – or perhaps, more realistically, it’s gently closing the door on the past before the classic series plunges into its final, Ace-focused story arc. The Doctor, so often one step ahead or manipulating events in Season 25 is now the one being manipulated, caught in Mordred’s diversionary attack on the UNIT convoy while Morgaine seeks the true prize of Excalibur. The Brigadier is brought back for one last trip around the block before he hands the baton to Bambera (an idea that’s only partly discounted by the old soldier’s stubborn refusal to die), and it’s nice that his final TV adventure with the Doctor should be with another funny little man, like the first version he met.

Next episode: Battlefield – Part Four