At the top of the episode, a slightly fluffy Hartnell is delighted by the chance to get involved on some of the action traditionally reserved for Ian – ‘I tend to forget the delight and satisfaction of the gentle art of fisticuffs!’. He and O’Brien continue to be a brilliant pairing. While the Doctor has it all worked out and just wants a good night’s sleep, Vicki is full of questions (that helpfully explain the plot) – it’s exposition, but very cleverly and humorously done.

After this wonderful opening, it’s a bit of a come down to join Barbara and Ian for the serious business of being enslaved. The slave galley is quite impressive, and Barbara’s cell is suitably grim, but there is a slight sense that there are two entirely different stories taking place here – one a light-hearted Spooner thriller, and the other a rather sober and semi-educational piece about the brutalities of the Roman Empire. It’s obvious which one the writer’s heart is in.

That said, director Christopher Barry makes it all hang together. The shipwreck scene merges some obvious stock footage with a well-staged (and wet) studio, before cutting to a well-attended slave market where Vicki and the Doctor wander past, oblivious, just missing Barbara’s presentation to the baying crowd.

The mix of the Doctor and Vicki’s feckless history tourism (which is very new series) and Barbara’s genuine perils are connected by the plotting Tavius, and converge on the household of Emperor Nero. Hartnell and Derek Francis go all out with their very funny comedy business about a footstool and a lyre. Meanwhile, Ian gets to run the gamut of miserable Roman fates – having escaped galley slavery he’s now set for a date with the lions in the arena.

Next episode: Conspiracy