The festive period is a busy time for Time Lords – last Christmas Matt Smith was battling the Daleks before regenerating as Peter Capaldi – and this year’s Doctor Who special is no exception.

Writer Steven Moffat has described ‘Last Christmas’ as a buddy movie mash-up of Miracle On 34th Street meets Alien, with a decent fright factor. And it features Hot Fuzz star Nick Frost as Santa Claus.

“For the first time the Doctor comes face-to-face with the real Santa Claus and that is totally kosher,” Peter says, in the Daily Express.

“It’s not a robot dressed up as Santa, or an alien being. It’s absolutely Santa Claus. It’s the real thing.”

One of the running jokes in the episode is the slightly antagonistic relationship between the Doctor and Santa.

Filming a Christmas special was a strange experience for a lifelong fan of the show, Peter admits.

“Since the specials started [in 2005] I’ve made sure we build our Christmas Day around it – not realising that, one day, I would be part of it as well. It’s a bit terrifying because it’s in that old Morecambe and Wise slot. There’s always a bit of concern whether it will be successful or not.”

The action begins when Santa crash-lands his sleigh on Clara’s roof. Shortly afterwards, the Doctor and Clara (Jenna Coleman) find themselves on a polar base “under attack from terrifying creatures”.

Something “very powerful and deceptive and not to be trusted,” says Peter. “And lethal – in a final way.”

Lethal for who?

“You’ll just have to wait and see. But some strange things happen to Clara,” adds Peter.

Peter says he will spend Christmas Day strapped in front of the telly, pushing chocolate into his mouth. But as for watching the special, he’s undecided.

“I’m not crazy about watching myself,” he admits. “But I like Doctor Who so I’m trapped! I think I probably will watch it, yeah.”

Doctor Who, BBC1, Christmas Day, 6.15pm