With snippets pinched from Alien and The Thing, not to mention various other Doctor Who episodes, this year's festive special was a handy way to cram all your Christmas TV repeats in to one convenient hour.

But despite the many borrowed themes, the story was able to stand alone. Last year's Doctor Who special was a rambling, jingle-belled mess but this year's was neat and coherent whilst still making space for the usual twinkly helpings of festive cheer. And when Santa and his elves appeared, it still cleverly avoided slipping off into the twee stuff of last year's Christmas episode.

However, there were still some moments when it all threatened to go soft. The opening scenes squeezed as many Christmas elements in as possible, with snow, jingling bells, a sleigh, reindeer, elves, and then the big man himself, played by Nick Frost. As the elves capered around, mocking Clara for not believing in Santa, I felt my toes curl. There are countless cheesy Christmas films on TV at this time of year, so I don't need Doctor Who for my dose of jingly nonsense. Perk up, and get going with a real plot!

Mercifully, Capaldi barged in on this winter scene, bringing with him aliens and horror. What a relief. The scene moved from a snowy rooftop to a bleak Polar research station where alien face-huggers (or, in this case, Dream Crabs) latched onto everyone, sending them into deep, vivid dreams. As the characters slept, the crabs went to work on sucking the brains and life from their sleeping bodies.

Clara's dream took her back to Danny. They were sharing a warm Christmas Day, at home together by the twinkling tree. The Doctor barges in (again, here he comes to stop the show reeling off into festive sweetness) and tells Clara this is a dream and she must awake. Every moment she dwells here with Danny takes her closer to death.

This may have been a sly dig at what modern Christmas has become. Her beautiful festive dream isn't real, she's told. The tinsel and baubles are all fake. 'It's keeping you warm and happy whilst it's eating you!' shouted the Doctor, and was he speaking of the Dream Crabs or capitalism? This fuzzy, fairylit Christmas is not authentic. Wake up. Clara! Underlining the point, dream-Danny smiled like a zombie, saying, 'mince pie anyone?'

Danny was futile in this episode, only appearing so he could populate Clara's dream, and he was the bland, nice boy he's always been. Even as a dream conjured up by an alien he was still just sweet and dull, warning Clara that 'every Christmas is last Christmas', so treasure each one. Bleurgh! Give me the gruff Doctor any day, who soon elbowed soppy Danny aside to warn everyone that the aliens have 'weaponised our dreams against us!'

He pulls them out of their dreams, only to discover that the awakening was simply another dream, and they remain trapped, as if in a nightmarish Russian doll where you emerge from one dream only to find another, and yet another.

Thankfully, Santa saves the day, making a reappearance which justified the festive capering in the opening scenes. There followed some brilliant, prickly exchanges between Santa and the Doctor as they bristled and squared up to one another to see who was top dog on the Polar base.

But any gruffness in the Doctor vanished when he took the reins of Santa's sleigh. He was transformed into a giddy, laughing boy as he guided the reindeer across the starry sky, and that provided a lovely festive touch without it turning twee and saccharine.