The Kings Speech (12A)

It's the sort of thing we do awf'ly well. The King's Speech extends a loose succession of royal films – Mrs Brown and The Queen are its forerunners – that reflect the cockeyed vision of class in our sceptred isle. It is a vision skewed between an old deference to "the quality" and a newer democratic resistance to bowing and scraping. We no longer think of the royals as our betters; but they have just enough mystique for us to be curious about their human side. This film tickles us with the once-outlandish idea that a commoner could be – just fancy! – the friend of a king.

The king in question is George VI, formerly Albert, the Duke of York (Colin Firth), whom we first see about to address a crowd at Wembley in 1925. He looks more like a man about to step up to the gallows, for Albert is afflicted with a terrible stammer, and the large clunky microphone rearing in front of him will amplify his every tortured gulp and gasp. About him his courtiers look embarrassed, while his subjects look merely bewildered. That stammer might have become an historical footnote, but 11 years later his older brother David would, as Edward VIII, abdicate as king in order to marry American divorcee Wallis Simpson. Requiring a voice to go with his untimely accession to the throne, Albert tries various quack remedies, including marbles in the mouth, but his tongue refuses to untangle.

Meanwhile, an Australian expat named Lionel Logue (Geoffrey Rush) is failing to impress at an acting audition. He earns a living as a speech therapist in a grotty basement office on Harley Street, where one day a certain well-spoken lady arrives seeking a cure for her husband's speech impediment. She would be Elizabeth (Helena Bonham Carter) – the future Queen Mother – and her husband, dawdling in the shadows, none other than Albert. "What should I call you?" asks Logue. "Your Royal Highness," he replies. Logue calls him "Bertie" instead, thus setting up a comedy of manners between a jolly Aussie commoner and his morose, exasperated monarch. Can impudent colonial know-how enable the royal stiff to unbend? Logue has failed as an actor, but he turns out to be a rather good director, coaxing from his fearful patient what may in time be the performance of his life.

Tom Hooper, the actual director, modestly confines the action to interiors and lets the slyly witty script, by 73-year-old David Seidler, tell its story. It is a nice touch of Eva Stewart's production design to project their duologues against the shabby, flaking wall of Logue's office, a stagey backdrop in front of which this odd couple must improvise their relationship. Logue, having established his my-place-my-rules principle, is no less uncompromising in his techniques; he discovers that Bertie, tongue-tied by decorum, can swear fluently, turning the air blue in a scene that earned a disapproving "R" cert from the US censors, but will thoroughly amuse everyone else.

Inevitably, as trust begins to bond the two men, Logue comes to play psychotherapist as much as speech therapist, uncovering a lifetime of hurt and humiliation, which Bertie has hitherto borne in furious silence. We take the hint that he has been bullied by his father (Michael Gambon as a blustering George V) and has already suffered the pointless corrective of turning his natural left-handedness to right. He seems to get on with his more confident playboy brother David (Guy Pearce, superior in manner and cheekbones), yet otherwise exudes a poignant sense of isolation. "What are friends for?" Logue asks him. "I wouldn't know," he replies.

What lifts the film, lends it a seemly dazzle, are performances of a very high order. I have been agnostic about Colin Firth for years, having watched his Darcy-esque hauteur dwindle into increasingly stiff-keyed, wooden variations: he has essentially been impersonating a wardrobe. He warmed up the emotional repression of a bereaved professor in last year's A Single Man, though he was overpraised and, in Tom Ford's exquisite clothes, frankly incredible as an academic. Here he has the brooding look of a constipated frog, with a similar vocal range, but he tempers the king's sudden bursts of rage (at one point he calls Logue "a jumped-up jackaroo from the outback") with a human sense of frailty: drawing from a deep well of melancholy, he seems to know what little fun he is. Geoffrey Rush, as the jumped-up jackaroo himself, is wonderful, a puckish foil withholding deference while gently twitting his royal master into a semblance of amity. How true this is to the men's actual relationship I couldn't say – one suspects a certain royal snobbery has been deleted to taste – but both Rush and Firth play off each other very deftly. Logue: "Do you know any jokes?" Bertie: (long pause) "Timing isn't my strong suit."

The film's two historical crises are shrunk to fit around the double meaning of "the King's speech". The first is his brother's abdication, which thrust Bertie into the public eye and forced him to find his voice. The second is the outbreak of war with Germany, when, as the film tells it, the new king committed himself under great pressure to being word-perfect for his national broadcast. Perhaps it really was like that, and radio listeners in 1939 took heart on hearing George VI's words of calm resolve. But we shouldn't exaggerate its significance, either. Don't we believe that people would have fought on exactly as they did, with or without the monarchy's encouragement?

The King's Speech is fine middlebrow entertainment, well put together and beautifully played by its leads. It tells the story of an affliction bravely overcome. It may help Colin Firth to win an Oscar. But I don't think we can say it helped us to win the war.