Peter Capaldi 'would consider Doctor Who appearance on Big Bang Theory'

Doctor Who star Peter Capaldi has said he would consider a guest appearance on US comedy The Big Bang Theory.

The smash hit American sitcom about a group of socially-awkward scientists has made numerous references to Doctor Who over the years.

When asked if he would like to join the list of famous guest stars, who include former Marvel Comics head Stan Lee and Professor Stephen Hawking, he said: "I might."

He added: "Depends what the script is like. Depends how good the gags are. I'll do anything for good gags, I'm an actor, I'm a tart. I'll do anything for a laugh."

Speaking at the Doctor Who Festival in ExCeL, London, he was joined by Doctor Who executive producer Steven Moffat, Sherlock co-creator Mark Gatiss, Michelle Gomez who plays Missy and Ingrid Oliver, best known as Osgood.

Capaldi, 57, admitted to some trepidation about Heaven Sent, the one-hander to be broadcast on November 28 in which the Doctor will be the lone character.

"I was quite nervous about the idea that maybe the audience might get bored of me quite quickly because this is the only voice they've got to listen to and this is the only face they've got to look at and it might get dull, but the story is so good."

In the Christmas special, the Time Lord will be joined by Alex Kingston, who makes her return as River Song.

Anticipation is already high because the fellow time traveller will finally meet her husband's new incarnation.

"Alex is fantastic," Capaldi enthused. "It's great to work with her. I'd never met her before. Of course she's a veteran of Doctor Who, she's been involved with it longer than I have so it was quite scary from that point of view. But she's a delight."

On the subject of the Christmas episode, Moffat revealed it is "funny".

"We're getting quite dark towards the end of the series, I wanted to lighten it up again and remind people that it's a chase, it's a romp, it's funny. It's a very funny episode," he said.

"I missed writing River and when I thought I could have River back - because I'm allowed - I just thought, that's cheered me up a bit."

Moffat continued: "At first, she doesn't know who it is so that's fun. I didn't know which way Peter was going to go with it, but I think the Doctor's just got - even in his current Caledonian form - a walloping crush on that woman."

Doctor Who writer Gatiss wrote ninth episode Sleep No More, which will be broadcast on BBC One on November 14.

"My avowed intention with this episode was to essentially write it as a horror movie and rein it in, but we didn't," he admitted.

"It is very, very, scary - and I hope people find it so. It's all about primal fears. I'm slightly insomniac myself and the idea came to me one night, lying awake, staring at the ceiling. I thought, what if there's a reason why we sleep?"

He continued: "What if it's more than just a physical need? What if it's a good thing because it keeps the monsters away? I've got a terrific new monster and it's a very spooky story and a great cast."

The Doctor Who Festival runs at ExCeL on Friday 13, Saturday 14 and Sunday November 15.