‘Now the dream outlives the dreamer and can never die.’ This fulfils the same function as The Runaway Bride: on the back of the Doctor losing a beloved companion, he needs a new friend to remind him why he does what he does. Which means Clara has to be this Doctor’s Donna, shocking him out of his gloom and drawing him into a new adventure through sheer force of will.

Whereas Donna did it by being strident, Clara does it by being persistent, demanding answers and refusing to run away when she has the chance. After a brilliant preview in Asylum of the Daleks, Jenna-Louise Coleman continues to impress with two sides to Clara, the working-class barmaid and the proper governess, hinting at the multiple other lives of Clara scattered through time and space. She trails the Doctor back to his cloud, meets with Madame Vastra to pass the one-word test (as she will again, in Deep Breath) and gets as far as being presented with a TARDIS key – before she falls to her death, a shocking moment for an audience teed up to expect her to stay.

Clara wooing the Doctor powers the story, and her death naturally draws it to a close as the snow of the Great Intelligence is washed away by the tears shed over Clara’s broken body. The cold loneliness of Dr Simeon (an aloof Richard E Grant) is no match for the power of the warm feelings Clara creates in others. It’s an unusually RTD-ish resolution for Moffat, as humany-wumany emotions trump timey-wimey cleverness, and even if it doesn’t entirely convince (is snow really a mirror?) its heart is very definitely in the right place.

However, it does mean that the dawn of the Great Intelligence and its unlikely plan to take over the world with snowmen is very much a B-plot, and fans who looked forward to an origin story might wonder how this all fits with The Abominable Snowmen, where Padmasambhava was already possessed by the Intelligence in 1892 and working to its design in Tibet. Moffat quietly skips over that origin story and makes this an alternative lead-in to The (soon to be rediscovered) Web of Fear.

I enjoyed this at the time: it’s filled with very funny sequences, mostly involving Strax (the adventure of the Memory Worm could be a minisode in itself). I like the cheeky crossover with Moffat’s other hit show, as the Doctor plays Sherlock Holmes to Ian McKellen’s sibilant, gloating alien Moriarty. Matt Smith’s performance is a step up from much of the first half of Series Seven, as he goes from curmudgeonly and withdrawn to re-engaging with being the Doctor as he adventures with Clara.

I also enjoy the visuals, which have the logic of a fairy tale (a staircase to the clouds; the frozen governess). I probably liked the crazy angles of the previous TARDIS interior better than most, but the new set that debuts here looks great. The only thing I’m not sold on is the title sequence – a mess of fizzes and pops that’s much too pink to exist outside Season 24. Otherwise, this is Christmas goodness.

Next Time: The Bells of Saint John