A crowded room. Friends with tired eyes. It could only be the press launch for the Doctor Who Christmas special where BBC top brass, Doctor Who production staff and assorted hacks and ne’er do wells join in the annual celebration of that most seasonal of figures: the Doctor.

We know the drill by now – once bitten and twice shy, and all that. Whatever your expectations are for Doctor Who during the rest of the year, at Christmas, you should expect an episode that’s a little flabbier than usual – a little less lean in the telling.

Except, this year, Steven Moffat does something a little different, proving that, no matter what his critics may say, he is, in fact, someone to rely on. From the pre-publicity, you’d assume that this was the most Christmassy Doctor Who special to date, and yet, what’s notable is: if you take a certain Mr S. Claus out of the equation, it’s an episode which could happily play in Who at any other time of the year.

Sure, all those cheesy Christmas elements are in place – not just Santa, but Rudolph, the elves and, of course, the tangerines (oh, the tangerines) – but these elements, while intrinsic to the story, are also, to some degree, sleight of hand. Even Santa himself – undeniably the most controversial ingredient of the episode – is used as both a character and a conceit. Yes, he’s the real deal; but he also doesn’t compromise the Doctor Who universe by being in it.

Playing the part of the jolly bearded one, Nick Frost is – well, he’s a little bit Nick Frost. Snarky and geezerish, it’s a performance that’s resolutely unsaccharine and comes with the in-built knowingness we have come to expect from Moffat characters. But a little bit of irony is needed when you’re dealing with a character as iconic as this, and, for all the gags relating to Santa’s presence in the story, at heart, Moffat takes the idea of Santa very seriously indeed.

This is a Doctor Who story which celebrates, and also reveres, the gleeful absurdity of Christmas. There’s some Noddy Holder, a little bit of dad dancing (although not from a dad)… But it’s also one of the most sci-fi Christmas specials we’ve ever had: happily, and self-consciously, riffing off Alien and The Thing to give us an isolated scientific base, at the North Pole, under threat from a suitably chitinous alien within.

Narrowing down the cast, and making a conscious effort to ramp up the tension, has the effect of throwing a focus on the supporting characters in a way that isn’t always possible in mad, frenetic Doctor Who. There will always be a joy in hearing Patrick Troughton’s sons speaking in that same, bedside-warm timbre as their dad, but, although Michael Troughton is a welcome addition to the cast, it’s Faye Marsay who really impresses here.

Like all good Doctor Who stories, this juggles the mundane with the frivolous, the fantastical and the sci-fi – and also takes a moment or two to register just how much fun it’s having in the process. But if Steven Moffat is confidently freewheeling with the imagery of the festive season, he also hasn’t forgotten the sombre events of last month’s finale. Gallifrey is addressed and Clara isn’t suddenly reset into default companion mode just because it’s Christmas Day: on the contrary, her grief for Danny Pink is a key motivation for her behaviour in this episode.

The tenderness and tension between the Doctor and Clara is still there, and leads to some moving final scenes in which Jenna Coleman does some of her best work to date. But, for the bulk of the episode, Capaldi gives us a Doctor who is happily and confidently more himself than ever.

Taking charge of the scientific base, with no time to question whether he is a good man or not, he is afforded both the natural authority of the character and also one moment of pure childish glee that proves decisively that this Doctor still has a fire in his heart. Little wonder that we in the press party were so warmed and charmed by the episode.

We weren’t the only ones to be so. Leaving the press screening, arm in arm with his dad, Steven Moffat’s son turned to him to say, bathetically, ‘It’s much better than last year’s.’ (After some probing, it turned out, by ‘last year’s’, he meant 2011’s ‘The Doctor, the Widow and the Wardrobe’.)

‘Everyone’s a critic,’ was Moffat’s grizzled response. But hey, the boy is right! ‘Last Christmas’ is not only better than that particular Christmas episode, but also better than several other Doctor Who Christmas specials we can think of. Others have been more lavish or more high-energy; but it’s hard to think of any that have been quite so clever or so sophisticated in their conceits.

Airs at 6.15pm on Thursday 25 December 2014 on BBC One.

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