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 honey-moon. 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 with a giggle.

It is, of course, Moffat’s first Christmas in charge of our favourite time traveller’s adventures – and stars Matt Smith (the Doctor), Karen Gillan (Amy) and Arthur Darvill (Rory) are also popping their festive Tardis cherries.

“I’ve always wanted to be part of the Christmas Doctor Who experience,” reveals Smith. “And I think this is one of the most Christmassy and inventive Doctor Who stories so far.” 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.

“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!”

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.

Soprano Katherine Jenkins will be making her acting debut in the episode: “To be honest, I didn’t think I really wanted to act,” she confesses. “But when I got the call to do Doctor Who, it really excited me. I got a call on my 30th birthday to say I’d got it. It was the best birthday present I could have asked for!”

Smith said of his co-star: “Katherine looks like a princess, and boy can she sing. It’s exactly the type of casting we want – someone fresh, exciting and new.”

That sounds like a description of Smith himself before he took on the role of the iconic Time Lord – and if this episode is anything to go by, we’re going to enjoy plenty more Christmases with him for years to come.

• Doctor Who: A Christmas Carol is on BBC One on Christmas Day