It’s difficult to remember what BBC One’s Christmas Day line-up was like in the dark ages before Doctor Who was revived.

There was the Queen’s Speech – still proudly soundtracking post-lunch snoozes to this day – and the freeze-dried corpse of Top of the Pops continues to be wheeled out as a reminder that it was once a show of some importance, but beyond that, it’s all a bit hazy. In fact, it’s like trying to picture the first time your heart was broken: remembering isn’t actually very hard at all, but why the hell would you want to?

Of course, the best way of looking back is by looking forward – something the Doctor is compelled to learn in his eighth festive adventure, whilst simultaneously battling a reluctantly detoxified Withnail and an insidious snow globe that talks like Bad Gandalf and makes evil snowmen out of dandruff.

Our hero also dresses up as Sherlock Holmes, hangs out with lesbian lizards and subservient Sontarans, and hooks up with an impossible, irrepressible and irresistible new companion to create the finest time-travelling Doc-and-Clara team since Back to the Future Part III and the best Christmas episode of Doctor Who yet.

From the outset of the iciest of cold opens, in which Richard E Grant’s chilly bastard Dr Simeon sacrifices his starving staff to the equally ravenous snow (‘I said I’d feed you; I didn’t say who to’) and the Doctor displays his borrowed Harold Lloyd specs, stovepipe hat and new, non-interventionist policy, it’s clear that much has changed in the three months since we left the last of the Time Lords in Central Park, both for the character and the show that bears his favourite question as its title.

There’s a distinct freshness to the programme, evident in its revamped visuals – the Empire Strikes Back lava lamp of the new opening titles, with the Doctor’s shadowy, grinning face zooming through gaudy constellations like a happy ghost, the vastly-improved TARDIS console room interior, wintry scenes of Victoriana that for once don’t look as if they were filmed in 21st Century Cardiff on a July afternoon – and its music, which is Murray Gold’s best in some considerable time, but it’s in the Doctor himself that the differences are most apparent.

Matt Smith has always been excellent; now he’s bloody astounding. The Doctor is still unmistakably the Doctor, even when he’s all glum and wistful and living on a magic cloud like Mother Nature awaiting the arrival of SuperTed and Spotty, his compassion and kindness towards Clara evident even when he doesn’t want to pal up with her, but there’s a melancholy maturity to him, something newly adult about this most eternal of children, as if a millennium of the universe’s ungrateful cruelty is finally starting to tell.

Quite how Smith manages to cram a thousand years of painful experience into his 30-year-old cheekbones is as much a mystery as how he manages to make his patently ridiculous Holmes impression so enjoyable (Steven Moffat must be taking the piss out of himself here, particularly as there are hints of David Arnold’s Sherlock theme in the scene’s incidental music) and his deliberately awful jokes (‘Takes one to snow one’) so hilarious,  but he does everything with such stylishly consummate aplomb that the prospect of him relinquishing the role is more unthinkable than ever. More than any of his predecessors, he is the Doctor.

But what’s even more impressive is how quickly Jenna-Louise Coleman has become the companion, even though she hasn’t actually joined the TARDIS crew properly yet. Building on her excellent debut in ‘Asylum of the Daleks’, she imbues Clara with all the brashness, wit and courage required for the role of the Doctor’s human better half, but combines it with a underlying vulnerability and unconscious sense of otherworldliness, as if the character is dimly aware that there’s something unique and outlandish about her.

‘I don’t know why I’m crying,’ Clara says, shortly before her dying tears save the world from the Great Lack-of-Intelligence (who try to act covertly despite having their initials emblazoned all over the shop), and it’s the myriad don’t knows about a character who has now died twice and come back all the better for it which are the hook for the rest of the present series.

The mystery of Clara Oswin Oswald has rejuvenated the show as much as it has the Doctor himself, and if the next eight episodes match the standards set by ‘The Snowmen’, the fiftieth anniversary of Doctor Who is kicking off with all guns blazing. The best way of looking back is looking forward.

Aired at 5.15pm on Tuesday 25 December 2012 on BBC One.

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