The new Doctor comes more sharply into focus in this episode, which starts to give Pertwee the opportunity to define how he plans to play the part: flexing from spiky condescension to charm to sheepishness in the space of a couple of minutes. Dismissing the ‘primitive’ UNIT lab, he woos Liz into stealing the TARDIS key from the Brigadier, trying to make a run for it, and then admitting defeat. When I was a teenager Pertwee used to get a bad rap from the upper echelons of fandom, but he’s instantly likeable because the arrogance and pomposity is only ever a pinprick away from being deflated.

In the absence of a working time machine, it’s also interesting to see the era’s obsession with gadgets starting to surface. Last week the Doctor had a special homing watch that allowed him to track the TARDIS, and here we learn the TARDIS lock has a ‘metabolism detector’ and is ‘dimensionally transcendental’. It’s a bit odd how much time is spent discussing the TARDIS’s abilities here given no-one’s going to see inside it all year, but I guess it does show what the Doctor’s lost.

I like how much effort is being put into the supporting characters in this story: one of Robert Holmes’ strengths as a writer is the vividness of even relatively minor roles. Meg Seeley is established as a bit of a nosey nag, but not unlikeable, and the scene where she’s confronted by an Auton, and fights for her life, establishes both the ruthlessness of the monsters and the harder edge of Season Seven: we never saw the invading Cybermen beat an old woman or shoot shoppers. So it’s a definite relief when Liz emphasises that Meg survived the Auton attack.

Sadly, brave Ransome, who only ever wanted to sell dolls to Americans, doesn’t make it out alive: a really good performance by Derek Smee (doing a convincing impression of a man in shock and then desperate for his story to be believed) is rewarded with a memorable death that re-emphasises the terrifying relentlessness of the Autons. And Hugh Burden is great in his shiny-face make-up, never shaking hands or making eye contact, and giving the impression that half his mind is somewhere else: not thinking about the cheque, but controlling the Autons.

This is a really solid third episode that convincingly pulls together the threads set up in the first half – Scobie’s waxwork, Ransome’s suspicions, Seeley’s petty criminality. And for any contemporary fans, there’s even a hint that there might be a returning villain involved when Liz declares that the control sphere contains ‘some form of Intelligence’.

Next episode: Spearhead from Space – Episode 4