This is one of the great comedy episodes of Doctor Who, with Holmes extracting a huge amount of witty mileage from Garron and Unstoffe’s long con on the singularly humourless Graff. Unstoffe’s delight in his own improvised story of the ‘scringe stone’ is brilliant, and highlights how well this is performed: had everyone been doing things as broadly as in some of Season 15, the comedy yokel wouldn’t have worked nearly as well. And while no-one could accuse Iain Cuthbertson of giving an understated performance, it’s completely right for Garron, who’s one of the slipperiest customers the Doctor’s met. His lapse from Jagoish master of ceremonies to Cockney villain is wonderful, especially because the implication is neither is the true Garron. He’s always playing to the audience.

To an extent, the Doctor and Romana are spectators in this. But they’re very active spectators. The Doctor’s clearly impressed by Garron’s patter (however much he might call it ‘old guff’), and his intervention in the con, claiming he and Romana are also from ‘the north’, is huge fun. And as both Doctor and Garron want to steal something from the relic room, they’re brought into inevitable conflict. Romana, meanwhile, gets to spout some amusing psychobabble and learn a thing or two about the art of crime (her ‘oh’ as she processes that you can’t be a successful crook with a dishonest face is wonderful).

On top of this, there is Holmes’ customary world building: he has the same way with words as Russell “Could’ve Been King” Davies or George RR Martin. We get references to the Graff’s Levithian Throne, and noises off about the High Court of the Cyrrhenic Empire (which all sounds very Frank Herbert). And director George Spenton-Foster is on the same page, bringing the ritual and ceremony of Ribos to life so that, like Peladon, we almost don’t notice the whole planet is represented by about three rooms.

Next episode: The Ribos Operation – Part Three