Steven Moffat has revealed more details on the upcoming Doctor Who Christmas spacial, The Husbands of River Song, giving his own personal introduction to the episode and a little more about the big bad King Hydroflax.

Introducing the episode, written by Moffat himself, Steven promises we’ll see what River gets up to when she thinks the Doctor isn’t looking:

“The Doctor is an all new man and has been for a while. It may have slipped his mind that out there, in a very tangled and complicated way, is his wife that has never seen this face before and doesn’t even know about this incarnation. We’re about to stand with the Doctor and see what River is like when she doesn’t know he’s looking. We’re about to see what River thinks of Matt Smith turning into Peter Capaldi.”

And the interplay between River and the Doctor is central to the episode, an episode described as a “big romp” by the show runner:

“River Song meets the Capaldi Doctor, that’s got to be fun - I’d like to write that. That’s what made me want to write. I knew it had to be a big romp for Christmas day and there’s nothing like River Song to make that evident - River brings a whole storm of camp glamour to it.”

Moffat seems to be in his element and throughly enjoying writing a lighter episode after some of the darkness of Series 9, proclaiming his love for all things Christmas:

“I like Christmas specials - I know some people don’t. Some friends of mine don’t like Christmas specials very much and they’re always complaining about all the tinsel, the goodwill and the twinkly stars, and the lovely snow on the rooftops. I love all that, I love Christmas as a day and as a festival. I love that it’s dark, twinkly and rich red, all those things I adore so it’s no hardship for me at all.”

And is it any different writing a Christmas episode of Doctor Who?

“Yes, you need to have a bit of Christmas in it, but that’s never felt to me like a tremendous impediment, it’s a hook to hang it on. Sometimes we go very Christmassy - ‘A Christmas Carol’ was incredibly Christmassy, so was ‘The Doctor, the Widow and the Wardrobe’ and ‘The Snowmen’ had the appearance of Christmas without being very Christmassy. Last Christmas is actually the least Christmassy episode we’ve ever done, except for the fact it actually had Santa Claus in it - I rather loved last Christmas. This year’s episode starts Christmassy and has a comedy romp!”

With both Matt Lucas and Greg Davies on-board, there certainly promises to be plenty of comedy.. but just who is King Hydroflax?

“King Hydroflax is a very bad King, who as it turns out is mostly cyborg - in fact only his head has remained. He’s a vicious, terrible and deeply stupid man and a dreadful tyrant. “

Doctor Who returns this Christmas Day at 5:15pm on BBC One with The Husbands of River Song, also scheduled to be broadcast on BBC America.