Very much more of the same after the first two episodes. By now, the police are involved, the Doctor has turned the tables on the villains, and the Chameleon’s plan to kidnap and replace individuals is clear. If this had been a 50-minute episode from one of the secret agent shows it emulates, this would be the point when there’s a punch up, and a quick tag scene.

But as this is 1960s Doctor Who and Innes Lloyd has decided that serials should typically be six episodes long to reduce costs, this is instead the first of what’s going to be the norm for the next few years: middle episode padding, where the third of four parts is instead crammed into 75 minutes of stuff happening much more slowly and repetitiously than it used to.

This isn’t to say there aren’t things to enjoy. Troughton is typically delightful: tricking and shooting down Spencer, escaping the hangar, resignedly revealing the truth to a disbelieving audience, and giving a wolfish grin as he winds up the Commandant. Colin Gordon is especially good as the incredulous bureaucrat, jaw dropping ever further as the Doctor calmly explains the Chameleon plot, and even more baffled by Inspector Crossland’s readiness to give the insane little man the benefit of the doubt. Meanwhile, Crossland plays the role the Brigadier will fulfil in later years: mediating between the Doctor’s outrageous claims and their dismissal by officials who just wanted a quiet day. There’s nothing here that isn’t going to be picked up in the UNIT years.

The other thing that works really well is the relationship between Samantha and Jamie. She’s clearly being set up as the new companion, twisting Jamie around her little finger to get him to help explore the Chameleon hangar, and then getting a moment of vulnerability that allows Jamie to comfort her – ‘No time to greet now.’ Later, when Crossland convinces the Commandant to allow the Doctor to investigate, she hugs Jamie – who pretends to be annoyed but obviously loves it.

But for all these nice character moments, the serial has settled into a holding pattern, going back round familiar sets and characters to reiterate what has already been revealed in the first two episodes. Samantha and Jamie’s trip to the hangar merely reveals more post cards, and the Doctor’s demonstration of the freeze ray just confirms what we already know. Even the cliffhanger whiffs of more of the same, as the young people we already know are being abducted are – shock, horror – abducted.

There are no real revelations: we already knew aliens were involved, that they are kidnapping young people and stealing their identities, that they have weapons ‘not of this Earth’, and the medical centre is where the identity theft is happening. The audience remain several steps ahead of the characters, as we’ve already seen all this happen in the previous episodes. The padding even leads to illogical moments like the Doctor outing Meadows as a duplicate, confronting him – ‘You must have a double!’ – and using him as a prop in the demo of the freeze ray, even as Crossland is warning, ‘We don’t want [the Chameleons] to get wind of anything.’

Next episode: The Faceless Ones – Episode 4