‘We must have changed something, right? I mean, people saw a monster in the Thames.’ I enjoy how this quietly subverts the expectations of an audience primed for timey-wimey, “am I a good man?” introspection and angst. At the top of the episode, Bill ponders the consequences of changing history or erasing her own future. Later, she confronts the Doctor about his attitude to death, and then he presents her with the same choice he gave Clara in Kill the Moon – destroy the beast or save it.

But this is refreshingly free of hand-wringing melodramatics. The answer to timey-wimey is ‘stop worrying about it’; the response to how many lives the Doctor has been forced to take is, ‘move on’, and the Doctor never walks away to push Bill to make a terrible decision. This is informed by the past few years, but, like the Doctor, it’s moved on from them. Throughout, Sarah Dollard’s script seems to be playing with past Doctor Who – Bill’s reaction to arriving at a point in history before the abolition of slavery, the Doctor’s response, and the realisation that Regency London was more diverse than the whitewash of history, is lifted from The Shakespeare Code. The ‘Loch-ness Monster’ swimming down the Thames is from Terror of the Zygons. The chained and exploited sea creature, fed with children against its will, is from The Beast Below.

I adore this. It’s a straightforward and accessible story with a heroic role for Capaldi, some great fish-out-of-water scenes for Mackie, and plenty of period detail (the Doctor getting Artful Dodgered; the nice contrast between the grime of the workhouse and the opulence – and racist statues – of the Sutcliffe house). There’s a realism to Bill’s reactions (Googling whether they changed history – and filling in the pay-off to the orphan story) which contrasts well with Clara’s increasingly Doctorish otherness. Dollard’s script is very good, but kudos as well to Moffat for being able to move on from his previous approach: I sense elements of what JNT was striving for when he wanted to move away from the invulnerability of the fourth Doctor and Romana to the more down-to-earth and vulnerable fifth Doctor and Tegan pairing – except this is executed better.

Next Time: Knock Knock