While there’s still a whole series of Doctor Who left to air before Peter Capaldi hangs up his sonic screwdriver, speculation has been rife as to how his incarnation of the Time Lord will be forced to regenerate in his final episode this Christmas.

And now series showrunner Steven Moffat (who is also leaving Doctor Who this December) has dropped a few tantalising hints about what to expect for the Twelfth Doctor’s final hour, which he says will be very different to previous Doctor Matt Smith’s regeneration.

“With Matt I had a sort of idea that his entire run should be in the pre-math of a battle he’s having at the end of his life,” Moffat told RadioTimes.com exclusively at the BFI and Radio Times Television Festival this weekend (see video below). “But with Peter I wasn’t quite sure. I wasn’t sure for a long time whether I’d be writing him out or whether he’d be carrying on with [new showrunner] Chris Chibnall.

“That fits his Doctor, though,” the screenwriter went on, before hinting that this less mapped-out path would be echoed in Capaldi’s regeneration.

“His Doctor feels sort of impulsive and in the moment and would do something reckless that you wouldn’t expect. That suits me.

“And I mean, you can overstate the difficulty of planning a finale for a Doctor. In the end, any Doctor Who story has such catastrophe going on in it, that he could be the one that gets the rock on his head.

“But I think I’m really happy with what we’re doing for his finale. I’m just working on it now. It’s quite early. I should be further through it, but there you go.”

Moffat went on to explain his less-than-emotional response to penning this final story, which he said was far from the misty-eyed sense of an ending most would expect.

“I know this sounds terrible, but I believe [former showrunner Russell T Davies] said the same thing, it’s not like that,” Moffat explained. “I’m just mostly worried about the script and worried about how I’m gonna make the story work.

“You don’t have time to be reflective and stare out the window and say ‘aah, days gone by.’ It just doesn’t – it’s too much work! Maybe afterwards, maybe when it’s all done I’ll sit and stare out the window. Though on past evidence of leaving things behind I haven’t. I don’t tend to really.”

“That sounds callous,” he admitted, “[but] what I mean is while this is an ending for me and Doctor Who, it feels like quite a happy ending. So that’s nice. It’s good to finish something.”

We’re sure he’s right – though at the moment, fans tearful at the very thought of Capaldi’s own departure might struggle to see his point of view…

You can watch the full interview with Steven Moffat in the video above

Doctor Who returns to BBC1 next Saturday at 7.20pm