In The Loop (15)

A palpable hit. When news came through that Alastair Campbell had seen In the Loop and pronounced it "boring", the film-makers must have rubbed their hands in glee: the principal target of their satire was nettled.

The film could wish for no juicier imprimatur. The peevishness seems such a schoolboy error on Campbell's part: much more stylish to have laughed along, or else to have risen above it and maintained an Olympian silence. I have a feeling that Malcolm Tucker, fictional counterpart of the ex-New Labour spin doctor, would have managed it better. He would probably have snarled, as he does to a hapless minister here, "You're gonnae rehearse saying nothing".

Tucker, the foul-mouthed governmental puppeteer, so scorchingly incarnated by Peter Capaldi in TV's The Thick of It, is the pivot on which Armando Iannucci's debut feature turns. The death's-head face and mongoose stare are very much intact, as is his habit of scaring people with his surprise entrances and his volcanic swearing: he opens his mouth and out shoots a geyser of asterisks. Because the film is partly set in Washington and New York, I had imagined the effing and blinding would be toned down for a transatlantic audience, but no: it's a super-sized, excess-all-areas festival of profanity, some of it childish, some of it wildly funny. There's just a lot of it, which in a half-hour format you don't really mind but over a full-length feature tends to pall. When, in the last 20 minutes, Malcolm hands over the bollocking baton to his deputy Jamie (Paul Higgins) – also Scottish, also teeth-baringly savage – you might feel you've had enough.

The set-up (it's not really a plot) starts with a government minister, Simon Foster (Tom Hollander) making a gaffe live on radio: he says that a war in the Middle East is "unforeseeable", a slippery word pounced on first by the media and then by Malcolm, who hauls in Simon for a lesson – delivered as if to a half-wit – on why he should never, ever risk telling the media anything it can use.

Malcolm hunts down words like a hound on a fox: he can't bear the idea of the truth escaping, so he bullies and cajoles and makes vicious personal threats. Woe betide anyone who uses a word that displeases him. "Purview", for instance. First he shoots the offender a look of incredulous scorn; then he sneers, "Purview? You think this is a fucking Regency costume drama?" Meanwhile, the hawks in Washington have adopted Simon as a mascot in support of their war, and soon he's in DC with his chief aide Toby (Chris Addison) to prepare for a meeting that will make him look important.

And there is the heart of Iannucci's satire. It's not the lies politicians and their handlers tell, or their venality, or their stupidity, though these also figure prominently. It's really about status, and the desperate scramble that ensues whenever that status is under attack. There's one marvellous scene when Simon and Toby, spotting their US counterparts (Mimi Kennedy and Anna Chlumsky) on their way to a meeting of the war committee, quickly decide to tag along after them – because they've no idea where the meeting is being held. (The two Americans are actually on their way to the toilet). It's the Special Relationship in microcosm: the US government leads, and the UK government meekly follows.

Without using its name, Iannucci and his writers are satirising the run-up to the invasion of Iraq, complete with dodgy dossiers, false "intel" and a supine UN: the first time as tragedy, the second time as farce. But this broadening of perspective doesn't really suit the format of what started out as a TV sitcom – The Office meets Yes, Minister, as it was described. The small, intimate scale of television was part of what made it work. Most of the time it was simply people in a room talking (or yelling, or swearing) at one another, and the audience, led by that nervy camera, were eavesdroppers on the crummy, lowdown business that passed for political decision-making.

Magnified on the screen that sense of hilarious intrusion is lost. The corridors of power, whether in Washington or Whitehall, look terribly drab, and the actors seem dwarfed by the space. Attempting to justify his big-screen graduation Iannucci summons a couple of star performers. Steve Coogan plays a borderline nutter who happens to be a constituent of Simon's in Northampton, while James Gandolfini is cast as a US general reluctant to go to war. It's not a convincing part for the one-time Soprano, though he does get a very funny scene when he tries making a calculation of army numbers posted to the Middle East – on a child's adding machine. Oddly, you can imagine it happening.

Wrested from its televisual habitat, however, it all looks very stretched: we are in The Thin of It. And despite Tom Hollander's pleasantly bumbling performance, Malcolm lacks an object truly worthy of his scorn. To be honest, I missed what Chris Langham brought to the failing minister of the TV series, not just the standard idiocy of the breed, but the insecurity, the laziness, the inability to think beyond his own survival in office.

Langham did a peerless job of really acting like a politician. In the Loop continues the demolition of what little faith remains in the political processes of this country. It is a rollicking entertainment for some of the time, and a sulphurous study in bare-faced cynicism pretty much all of the time. An achievement of sorts, though I wish I could have liked it more.

Have your say on 'In The Loop' at independent.co.uk/filmforum. We'll print the best responses in Wednesday's paper.