So, that’s that, then.

Annie has fulfilled her destiny and probably written herself out of the series in the process. Alex, Hal and Tom have become a cosy threesome, and Cutler-Nick-Cutler has burnt to a cinder.

As series finales go, you can’t say that it lacked incident.

From the opening scene, in which the young Eve is busted by Mark Gatiss’s Mr Snow, and all over the question of the colour of her eyes, there is an epic quality to the episode which suggests that anything can happen. But it’s the attention to detail that most impresses. As Snow’s car draws up, on which there is the tax disc, Nov 2022, it’s comforting to think that, in a future devastated by executions, pregnancy embargoes and resettlement camps, there’s still a care for vehicle licensing.

Mr Snow is a genuinely chilling creation – given to the sarcastic putdowns of a Headmaster, he operates with the languorous ennui of one for whom victory is a certainty and eternity both a birthright and a petty distraction. When he presides over a Last Supper peopled by children, renegade werewolves, and portly accountant-types, it is an image both epic and ordinary. This is a man for whom half a century is merely the afternoon off.

But the genius of Being Human has always been the juxtaposition of humour and horror. Those characters who are still not past the possibility of redemption are all dancing precariously between salvation and oblivion, and, as it’s the final episode, everyone is forced to make a choice about whose side they are on.

Brilliantly, for those of us who have loved Cutler since the first episode, he chooses the obliteration of his species. Rather less brilliantly, for those of us who wanted him to stay around, he has to endure a make-up job that makes him look like the Singing Detective put through a blender, and gets kebabed in the act of genocide, thanks to Annie‘s mother love. It’s as gruesome and tragic a death as we have ever seen in the show, made poignant by those final words: ‘So, this is how it ends. This is what it was all for.’

Personally, we’d have loved Cutler to stick one up to Mr Snow; but realistically, there was only ever one person likely to bring about the end game: the glorious Annie, who has been the beating heart of Being Human for four years.

Annie’s ending is beautiful and poetic, and crucially, in that we never see what is on the other side of her door, allows for the possibility of a return in the future.

For those of us with sentimental hearts – which, by this point in the episode, is almost all of us – the hope is that George and Nina are there to greet her on the other side, so certain are we that the afterlife is receiving her with love. But Annie’s love has reached out to, and sustained, so many characters in the series, there are any number of people who may want to greet her: Mitchell, Gilbert, even Lia…

No matter how promising the new line-up appears to be – and, as Mr Snow observes, ‘a new werewolf and ghost…: something about that format clearly appeals to you’ – the series won’t be the same without her.

But, if there is one thing that this series of Being Human has proved, it’s that, even without its initial players, the format endures and thrives. Now Mr Rook is on the scene, there are threats from yet more men in suits, and we would be devastated if the show wasn’t renewed for a fifth run to let them unfold. After all the hurly-burly is done, it is appropriate that so humane a programme should end finally on a note of friendship.

‘Why are you doing this? ’ asks Hal, and the answer cuts to the enduring heart of the show.

‘Because you’re my best mate.’

That sound you hear – it’s us giving a standing ovation.

Aired at 9pm on Sunday 25th March 2012 on BBC Three.

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