“How many regenerations did we grant you? I’ve got all night”

The catalyst to the Doctor’s actions, of course, is a belated but ultimately reasonably successful attempt to save Clara, last seen – excluding fleeting glimpses last week – dropping to the floor and, well, dying. And she still is dead, in that her heart has stopped, she no longer breathes and she has no pulse. But thanks to an extraction whatsit from the Time Lord stock cupboard, here she is.

Crucially, this time she sees what the Doctor’s gone through for her (superb acting too from Jenna Coleman as it sinks in, as it is when we see her overhearing the Doctor’s plan to wipe her mind near the end). How he’s spent billions of years – a number that’s hard to rationalise really; Rory’s one-time wait sounded longer, even that it wasn’t – refusing to give up on her. She’s telling the Doctor what he should – and shouldn’t – be doing. And she’s in control of some key decisions here. Including, ultimately, if she chooses to return to Gallifrey to die. Again.

And then, just to cap it, we also have the reversal of the Donna Noble moment.

For the last two series, the argument has been that Clara has taken on the Doctor role, since Peter Capaldi boarded the TARDIS. I suspect it’s no coincidence that the line “Clara who?” is uttered this week. And ultimately it’s Clara who does to the Doctor what the Doctor would be expected to do to others: she wipes his memory, or at least the part that remembers her. It’s a twist that makes things far more emotionally impactful, I thought.

After all, it reverses the usual farewell, and makes it all the more touching that it’s the Doctor struggling to put two and two together at the end, trying hard to recall her, and failing to do so. Credit, again, to director Rachel Talalay for the delicate balance she manages, and for her willingness to apply the brakes and keep things simple for big moments like these. It’s a complex visual finale, this, and she never loses sight of the story she needs to tell. Furthermore, visually, it’s an absolute treat.