"Twice Upon a Time"

When other Doctors have reached the end of their lives, this century, they have been fighting one of their bitterest foes - The Daleks, the Master and now, the Cybermen. Here, the battle is over, and we are left with a Doctor who, unlike his Tenth incarnation, is all-too willing to go. But he will not be alone...

This is, of course, Moffat's swansong, as well as Capaldi's and there are some familiar concepts that are expanded on. After giving us a Hell (the Teselecta) we are give a Heaven, in the form of Testimony – the NetherSphere without the horror. As with his first ever story for the programme, there are no real villains, because, despite the action-packed set-pieces, this is, more than any other a story about facing death, something that both of the regular characters have actually gone through.

Of course, the other main attraction is the Twelfth Doctor interacting with the First Doctor. The differences in character between incarnations are, as always a source of comedy, especially the First Doctor's rather less enlightened views of the role of women. David Bradley, after playing William Hartnell in An Adventure in Space and Time, now plays Hartnell's role. As with Richard Hurndall before him, Bradley doesn't try to impersonate the great man, but uses his considerable skills to essay an interpretation of the First Doctor that is compatible with Hartnell's. It is a powerful performance that highlights how much the character of the Doctor has changed, and not just his views on women – the speech that Moffat gives the Doctor for his motivation for leaving Gallifrey both ties in with the more detached, reluctant character in "An Unearthly Child" and is completely compatible with the man he will become. Making a very welcome return is Pearl Mackie, effortlessly confirming my opinion that Bill is the best companion of the 21st Century. We also have a nice role for Mark Gatiss who faces death in an all-too human context as the Captain it's the earnest, likeable persona which he does so well, very different from his other appearances. Playing the closest thing to an antagonist in the story is Nikki Amuka Bird, whose calm voice is perfect for the Glass Woman and her very distinctive face is recognisable even when captured as a transparent CGI creation.

Rachel Talalay again helms the story with great skill, again, making slower introspective moments work well with the action, of which we have plenty – the capture of the TARDIS by the Testimony Ship, the Ypres Salient and the horrors lurking around Rusty's domain. The production team are totally committed to making this tapestry bind and shine and the result is a visual feast.

And we are left with our leading man. Peter Capaldi has taken the Doctor into new places and successfully redefined the role. I had high expectations, as soon as his name was announced as the new Doctor and he has never disappointed. Here, he is a resigned, battle-weary hero literally, at the gates of Heaven, but he elects not to go through. Capaldi is funny, fierce, commanding and silly in his final performance as a regular, and he is wonderful and genuinely heartbreaking to see the Doctor's ring fall off his finger.

But it is not heartbreaking to see the owner of the hand that it slips off from. Jodie Whittaker is a phenomenal actress and I very much look forward to the most radical reformatting yet of a character that has survived and thrived for 55 years, precisely because reformatting is vital to the programme’s survival. Long may it continue...