We’re entering the last week where we can call Peter Capaldi the incumbent Doctor in Doctor Who. As of next Monday – Christmas Day – the mantle will be passed over to Jodie Whittaker in this year’s Christmas special, Twice Upon A Time.

It’s writer and showrunner Steven Moffat’s final Doctor Who too, and he’s been chatting about the tone of the episode in a new interview issued by the BBC.

“This episode is somewhere between a coda and drumroll. It’s a coda to the time of the Twelfth Doctor played by Peter Capaldi, and a drumroll to usher in the Thirteenth Doctor, played by Jodie Whittaker”, Moffat said.

“Approaching it, one issue I had was that The Doctor Falls was the end of Peter Capaldi’s Doctor. That episode saw the Twelfth Doctor stating what he stands for and standing on the hill on which he was prepared to die. That was the end of his story. But – as often happens in stories and real life – it didn’t end there. He kept going, he started to regenerate, so at Christmas what we’re going to see is a man weary and tired and, having made his point and having made his stand and given his life for something that matters, he has to learn just how to carry on after that”.

“But of course this being Doctor Who and Christmas it’s much warmer and hopeful than that, so in perfect timing walking towards him out of the snow he meets earliest incarnation. The William Hartnell version of the Doctor – played now by David Bradley in an astonishing performance – and the two of them are about to regenerate. Tonally it’s about saying ‘to hell with dying, let’s get on with living’. And what’s more Christmassy that that? It’s the turn of the year, a time for new beginnings, it’s the time when we start climbing back towards the light”.

Doctor Who: Twice Upon A Time screens on BBC One on Christmas Day, at 5.30pm.