The establishing shots do their job in clarifying the TARDIS’s latest destination: a familiar Wild West main street; cowboys wander through as the jaunty, jangling keys of saloon music play. This is Tombstone, and there is the O.K. Corral. The cowboys turn out to be the Clanton brothers, here to wreak bloody vengeance on Doc Holliday for the death of their brother Reuben.

All of which bodes ill for the Doctor and his friends – once again, the Ship has brought them to the site of an infamous massacre, and it seems inevitable that they will be dragged into its bloody events.

However, any suggestion that this might be a serious trip back in time is quickly dispelled the minute the Doctor leaves the TARDIS. He’s got toothache – wonderfully over-acted by Hartnell – and is in desperate need of a dentist. Perhaps it’s this, or maybe Steven’s puritan lack of sympathy – ‘Serves you right for eating that sweet’ – that makes the Doctor even sassier than usual. It’s a lovely sequence that’s the most extended bit of business Hartnell’s had for weeks, and he seizes it.

In fact, the whole episode feels like a comeback for the first Doctor after Wiles and Tosh sidelined him so often. He gets several great comedy moments, including making up a backstory for the crew – ‘fellow thespians’ – and then sinking reluctantly into the dentist’s chair as Anthony Jacobs’ convincingly dissolute Doc Holliday wields his pliers. It’s the broadest comedy the show’s done since the Monk episodes of The Daleks’ Master Plan, and a great realisation of Donald Cotton’s witty, wordy script.

Peter Purves again shows what a good match he was with Hartnell. The expression on his face when the Doctor declares he is a tenor, and his impotent fury as he’s forced to put his money where the Doctor’s mouth is and perform, at gunpoint, for the Clantons, are notably fun. Jackie Lane gets less to work with, but unsurprisingly Dodo does the best accent.

While the regulars are all on great form, it’s the guest cast that lets the side down, with a range of bafflingly inconsistent accents (West Country, Australian and Mid-Atlantic) and some brutal fluffs. While Anthony Jacobs and Sheena Marshe (as Kate) feel authentic, the Clantons sound like even they don’t understand what they’re saying.

Like the previous two historical stories, this relies on the Doctor being mistaken for someone else (Zeus, the Abbot of Amboise, Doc Holliday) which suggests either that the mistaken might have been an idea the production team was keen to exploit, or point to the potential limitations of getting the TARDIS crew involved in the historical stories. In any case, the climax of the episode – the Doctor, set up by Holliday, wandering forlornly like a lamb to the slaughter towards a Clanton ambush as Steven and Dodo perform The Ballad of the Last Chance Saloon – is great.

Next episode: Don’t Shoot the Pianist