‘I hate endings.’ This begins where Blink ended, with ominous, Dutch tilt close ups of looming statues implying that the Weeping Angels can take many different forms – including the Statue of Liberty. It sets the scene for an episode that’s a much more authentic sequel to Blink than The Time of Angels, with the same sense of creeping dread and the noose of Time closing around the characters. It even replays the scene of Sally meeting an aged Billy as private eye Sam Garner meets his older self.

However, this isn’t just a revamp of Moffat’s greatest hit. It introduces its own innovations – even more successful, I think, than The Time of Angels’. The Weeping Cherubs are both hilarious and horrifying, stalking Rory through modern New York and reappearing in 1938 to dispatch him to Winter Quay. And the secret of Winter Quay – a battery farm for Angels to continually harvest the timelines of their victims – is truly nasty. It pays off Blink’s observation that those Weeping Angels were stranded scavengers, whereas these are Angels at the height of their power and malice, formulating complicated plots and vengefully hunting down those that defy them.

It also uses River Song in a very different way. Now the Doctor knows who she is and is in on the joke, they have a relationship of equals, behaving like a squabbling married couple. For the first time, River is freed from being an enigmatic femme fatale (ironically, the role she’s playing as Melody Malone) and becomes a plausible companion, working with the Doctor to solve the mystery and come up with solutions rather than dropping mysterious hints and warning of spoilers. I wish we had more of Smith and Kingston together in this mode – but sadly, it’s the first and last time. Which, I suppose, is very River Song.

I enjoy this a lot, but it has a glaring problem. When Rose was trapped in a parallel universe, the show had already established (in Rise of the Cybermen) that the walls had closed, and there was no way back. But Moffat has just spent an entire series telling us that fixed points in time and recorded history can be cheated with just a little ingenuity because they are only ever true from a certain point of view. The ending, therefore, cannot be a plausible exit for Amy and Rory (and in the immediate aftermath fans came up with dozens of simpler ways than a Teselecta to pull the wool over Time’s eyes). Amelia’s last farewell does not work in a post-Series Six context.

A more likely explanation is that Amy doesn’t want to be rescued. Perhaps that discussion with River about the Doctor not liking endings hit home: Amy doesn’t want the Doctor to see her age and die any more than River wants him to see her broken wrist, and so instead she chooses to abandon the life she and Rory had happily built in The Power of Three to live through the most terrible decade of the 20^th Century. Which is an even more tragic farewell.

Next Time: The Great Detective