Ian continues to be menaced by stock footage – this week, of very docile-looking lions. Meanwhile, the Doctor bluffs his way through Tavius’s conspiracy. This leads to a hilarious moment where the Doctor declares he must get to the bottom of it and Vicki says, ‘see you later’ and wanders off to do her own thing – which finally involves an encounter with the poisoner Locusta. It emphasises how different from Susan she is – it’s hard to imagine Susan showing such independence from her grandfather.

There then follows another slapstick scene as a slave desperately tries to place Nero’s crown on his head just before Barbara is led in as a new slave for the Empress Poppaea – much to the delight of the obviously lascivious Emperor. The following Carry On Cleo scene of Nero pursuing Barbara up and down the palace corridors, just missing the Doctor, is the scene that everyone remembers. It’s quite funny, mostly because Hartnell grips the edge of his toga and declares ‘What an extraordinary fellow’ just like Hurndall does in The Five Doctors. Later he name-drops giving Hans Christian Andersen the idea for The Emperor’s New Clothes. Hartnell is thoroughly great – watch his funny business with a sword in the sauna scene with Derek Francis

It’s also quite nice to see Jacqueline Hill suddenly and wonderfully getting the funny bits after she had to do the drama last week, while Maureen O’Brien gets to be menaced by Locusta and then deciding to poison Nero on a whim to save a slave girl she doesn’t know is Barbara. It says so much about Vicki’s rebellious, independent impetuousness, which makes her such a fantastic character.

This leaves William Russell with the more thankless prosaic bits of the plot, investigating Barbara’s whereabouts and getting embroiled in a gladiatorial contest for Nero’s amusement. The rather grim end feels like a sop to the need for a cliffhanger that’s not quite in keeping with the black comedy of the rest of the episode.

Next episode: Inferno