It can’t be a coincidence that The Invasion of Time is one of the first Doctor Who stories to be made in the wake of Star Wars. The opening model shot – of a small ship dwarfed by a much larger one flying overhead – is a visual reference. But more than that, like Star Wars this begins in medias res: the story is already underway, with none of the familiar scene setting we’ve been used to for the last 15 years. The grammar of SF storytelling is changing, and this is one of the first beneficiaries.

I think this is a stunningly good first episode. Fair enough, it’s lit less atmospherically than The Deadly Assassin, and Gallifrey has begun its slide into soft-furnishing hell (Andred has a lovely standing lamp). Some of the comedy is laboured. I think the ponderous ceremony of going to Amber Alert is meant to be representative of the general speed and pomposity with which everything happens on Gallifrey, but it doesn’t quite work. Neither does the banter between Gomer and Savar, which slips in a key bit of plot information: ‘I’ve noticed lately, well, over the last decade or so, an enormous fluctuation in relative wavelength transduction over a particularly narrow band.’

But these are quibbles. This has all the ambition and inspiration that was missing from Underworld. The opening scenes are genuinely unsettling: Louise Jameson sells Leela’s confusion brilliantly, as the Doctor and K9 both seem to have turned against her. Tom Baker is astonishing, flipping between flippancy and fury in a moment as he upturns millennia of Time Lord tradition to demand a shotgun inauguration. His double act with John Arnatt’s Borusa is perfect: the patrician Sir Humphrey of The Deadly Assassin with an added streak of Victor Meldrewish scorn as he tut tuts about his old student’s behaviour, but is smart enough to read the hints the Doctor is giving him, and to go along with them. I get the sense that in the President Elect’s absence, Chancellor Borusa was quite happily running the show.

And where the comedy works, it’s very funny indeed. The Doctor’s royal walk through the assembled guards; the ‘boot cupboard’ joke from The Masque of Mandragora pushed even further, Leela’s gently flirtatious scenes with Andred. Some of the budgetary limitations work in the episode’s favour, as the rushed inauguration is suitably sparsely populated (insert outdated joke about the unhinged new President claiming it was the biggest crowd ever) and Gallifrey has a sort of gone-to-seed grandeur which is very 1970s Britain. This feels like the show has leapt forward about a decade in its approach.

Next episode: The Invasion of Time – Part Two