This is the story - some Austen scholars say "theory" - at the heart of Becoming Jane, a new biopic of the author. Anne Hathaway, the American actress last seen in The Devil Wears Prada, plays Austen. Scottish actor James McAvoy, very much the British actor of the year after his performance in The Last King of Scotland, plays Lefroy - a lad we first encounter in the film bare-chested and fighting in a boozy brothel. Austen purists may wish to have a little sit-down before going to see Becoming Jane.  "There's fire in it," says McAvoy enthusiastically of a film that offers a pacy, even "sexed-up" take on Austen. If there had been a Lefroy in Pride and Prejudice, Mr Darcy would have stayed in that lake. But, says McAvoy, we must understand Lefroy's laddish behaviour in the context of his obligations as a young man taken under the wing of his lawyer uncle in a time when to marry "correctly" was to marry for money.  "Lefroy had a lot of responsibilities placed on his shoulders from the age of 12. His mother had married badly, he was the eldest son, and he knew that if he made his way in the world, he would save his family's ailing fortunes. And if you know that from a really early age, you're going to go off the rails."  McAvoy attributes much of Becoming Jane's narrative brio to Hathaway. "I'm loath to use the word 'feisty' but," he continues with a grin, "she has made her feisty! Anne had very strong opinions about playing Jane, and I had very strong opinions just because I'm quite opinionated. So we clashed at first. But quite quickly we realised that we could be each other's best allies because we both cared about the same things: we wanted the production to have some integrity and not just be a British rom-com in tights."  Historical accuracy was also important. Having done his research, McAvoy firmly believes Austen did have a meaningful and ultimately life-changing relationship with Lefroy. He is also insistent that Lefroy - who eventually became Lord Chief Justice of Ireland at the time of the potato famine - would not have had an Irish accent, contrary to the thoughts of Becoming Jane's producers.  "It's completely disrespectful to an Irishman to suggest the English overlords all had Irish accents, just because you want a bit of the Irish blarney for the American audiences," he says.  Such forthrightness and confidence go some way to explaining why, at 27, McAvoy has come very far very fast. His TV roles, in White Teeth, State of Play and Shameless (on which he met his wife, actress Anne-Marie Duff), quickly led to a clutch of great and eclectic big-screen roles, from Mr Tumnus in Narnia to the student quiz geek in last year's comedy Starter for Ten.  It's largely due to McAvoy's jolting performance that Becoming Jane is more than just a handsomely mounted chick-flick or a Mother's Day treat. And this ability to transcend genre limitations bodes well for his upcoming action movie debut, in the comic book adaptation Wanted alongside Morgan Freeman; filming begins next month, but McAvoy is already looking rather buff, courtesy of some stints in the gym.  More exciting still is his immersion in another great literary world. Later this year we'll see McAvoy playing the male lead in Atonement, the keenly anticipated film of Ian McEwan's novel by director Joe Wright (Pride and Prejudice). Even this most coolly assured of young actors is finding himself swept up in the decades-spanning majesty of McEwan's epic account of love and war.  "I finished [shooting] that film last August," he says, "but I had to go in yesterday and record some additional dialogue. It immediately made me start crying again. I find it so easy to empathise with that story, because it's part of us, it's part of our history," McAvoy concludes with characteristic impassioned intensity. "It's part of Britain."
Rising star James McAvoy talks to Craig McLean about his role as the 'real' Mr Darcy in the upcoming  film about the author's life.