‘No man should hide himself, don’t you think?’ Given it’s a fairly straight adaptation of the most acclaimed of the tie-in novels, this is unsurprisingly great. In theory, it’s a fairly standard sci-fi trope (e.g. Buffy: Normal Again; WandaVision; Superman II; Deep Space Nine: Far Beyond the Stars), of a lead character becoming “ordinary”. This gives David Tennant the chance to create John Smith, a character distinct from the Doctor (although with anachronistically great hair) and play a slightly useless human, while Freema Agyeman gets to be the protagonist, desperately looking for a way to foil the alien killers looking to possess a Time Lord and make themselves immortal. The complication is that the Doctor hasn’t accounted for the human factor and falls in love, and not the dramatic, Rose and the Doctor kind of love, but the awkward, clumsy, human sort of love.

I tend to think these are fairly low-risk stories for a long-running series. At this point, there’s enough investment in Tennant’s Doctor that seeing him placed in an unusual situation and behaving out of character is almost certainly going to be interesting or amusing (for the same reason as those Star Trek Mirror Universe episodes are so popular). But it’s notable how much effort is put into this. The first 20 minutes are almost languid – frenetic flashbacks to the Doctor and Martha’s initial escape from the Family of Blood aside – which allows director Charles Palmer time to dwell on the little details.

The post-credits sequence introducing Farringham School subtly sets up wider themes of looming war, and the way these children are being groomed to kill as boys march in formation into classes where Smith recounts the history of Waterloo as flags flutter and He Who Would Valiant Be plays in the background. Later, in a neat nod to the novel’s cover, the Doctor in mortar board presides over a machine gun drill. Martha and Jenny grit their teeth as the boys patronise them; Smith stumblingly establishes a relationship with Joan, like something out of a Richard Curtis film. A Journal of Impossible Things gives glimpses of another life with monsters, other faces (the first onscreen confirmation that Paul McGann did count), ‘a girl in every fireplace’ (‘I have to protest, that is hardly me,’ responds Smith – tacitly acknowledging that episode’s mistakes).

It’s only once the Family arrives that the pace quickens, but even then, this is as slow as the new series gets. Animated scarecrows lurching through the countryside, gradually assembling human hosts for the Family, are juxtaposed with Smith’s tentative wooing of Joan, and Martha’s increasingly sour visits to a hibernating TARDIS. The pieces drop into place gradually: Tim pilfering the chameleon watch and dropping little hints of the Doctor for the Family to pick up; Jenny trying to get information from Martha; Sister of Mine overhearing Martha and Joan’s conversation at the dance. Impatient viewers might have found this hard going; everyone else appreciates if you don’t care about Smith and Joan, the next episode is going to be a damp squib.

What’s surprising in retrospect is how much this feels like set-up for the end of the series: in the first minute we get references to a ‘Time Agent’s vortex manipulator’ and the chameleon watch that both prove key to the climax of Utopia. Beyond that, the notion of a Time Lord hiding as a human, and the Doctor’s complete reliance on Martha to save the day while he’s incapable are both crucial elements revisited in the finale.

Next Time: The Family of Blood