Monsters, sharks, a honeymoon and a soprano, this year’s Doctor Who Christmas special is certainly pulling out the stops. Sarah Morgan steps into the Tardis to catch up with Matt Smith, Steven Moffat and Katherine Jenkins.

THE Doctor Who Christmas special has quickly become as traditional as turkey and sprouts, which is amazing considering that before 2005, when the sci-fi favourite was revived, there had only ever been one previous festive moment.

That came in 1965 when the first Doctor William Hartnell broke the fourth wall by wishing “a happy Christmas to all of you at home”.

Things are rather more sophisticated these days – and lead writer and executive producer Steven Moffat couldn’t wait to get his teeth into the project: “Oh, we’re going for broke with this one. It’s all your favourite Christmas movies at once, in an hour, with monsters. And the Doctor. And a honeymoon. And... oh, you’ll see.

“I’ve honestly never been so excited about writing anything. I was laughing madly as I typed along to Christmas songs in April. My neighbours loved it so much they all moved away and set up a website demanding my execution. But I’m fairly sure they did it ironically,” he adds.

Doctor Who-playing Matt Smith says: “I’ve always wanted to be part of the Christmas Doctor Who experience, and I think this is one of the most Christmassy and inventive Doctor Who stories so far.

“Steven keeps getting even more imaginative and the great thing about this episode, is that when Doctor Who and Christmas are put together, you combine the spirit of both those things.”

Explaining the plot, Smith says: “It starts off with Amy and Rory on honeymoon, but the spaceship they’re travelling on gets into trouble and needs to make an emergency landing on a nearby planet. However, they’re blocked from entering the planet’s atmosphere and with the ship nearing implosion, the Doctor has to try and work out what’s going on and how to save them.

“It feels very Dickensian, set in a mad futuristic world and it evolves into something even more magical than your classic monster Doctor Who episode.

“It features a wonderful shark which I was very excited about,” he continues. “I’ve always wanted to explore the aquatic – viewers can expect Jaws with a twist.” What Smith hasn’t revealed is that there’s also an old, Scrooge-like miser called Kazran Sardick at the heart of the story – and if the Doctor doesn’t make him change his ways, all hell will be let loose.

Sardick is played by theatrical knight Michael Gambon, the latest in a long line of illustrious guest stars to appear in Who.

“There’s no one better to play an old grump than Gambon,” laughs Smith.

“However, Michael also really makes you feel for this man and he can somehow turn himself into a little boy at times: he’s a very impressive actor.”

“It was a real privilege to work with Michael,” explains Smith. “I had a great time with him and he was really naughty. He’s so crafty and when I asked him about working with iconic actors such as Olivier and Bates he said the one thing they all had in common was they were naughty – and he’s exactly the same. He was very mischievous, constantly telling jokes and getting into the spirit of play.”

Much has been made of Katherine Jenkins becoming the second beautiful singer, after Kylie, to join the acting cast for a Doctor Who Christmas special.

Smith says: “With Katherine I was astounded by her professionalism.

Considering it was her first acting experience I thought she handled it with real craft and diligence. It’s exactly the type of casting we want; someone fresh, exciting and new.

“”Katherine looks like a princess, and boy can she sing; the way she controls her voice and the grace with which she sings is quite incredible.”

Asked if he believes in Aliens himself, Smith replies: “Absolutely. I’d be a charlatan playing this man if I didn’t.

Having spent so much time thinking about aliens and being an lien.

There’s definitely life out there.”

So what will the newest Doctor be doing on Christmas Day, a rare day off?

“I’ll be watching Doctor Who with my family of course,” laughs Smith.

“I imagine we’ll have a big lunch first and then we’ll sit down to watch the episode; the Doctor even gets to come down the chimney.”

■ Doctor Who: A Christmas Carol, BBC1, Christmas Day, 6pm