“Skinny geek”. “Pale wimp”. “Wispy-haired girlie”. Thank goodness none of these could apply to that rugged hero of many a female fantasy - Mr Darcy, from Pride and Prejudice, eh? When Colin Firth emerged dripping from a lake in the BBC's adaptation of Jane Austen's novel, a nation of women swooned that, yes, that is exactly how we'd imagined Darcy to look. As the novel says, he was a “fine, tall person”, with “handsome features” and “noble mien” and a sexy swagger of superiority.

But, oh dear, look what's happened. A 3in watercolour of Thomas Langlois Lefroy, the man thought to be the real-life inspiration behind Darcy, has just been made public and - how can we put this kindly? - we doubt that he'll be setting many hearts a-flutter. Though Lefroy, an Irish-born politician and judge who had enjoyed a flirtation in his early twenties with Austen, has a perfectly pleasant face in the picture; there's just no way that he has a six-pack. His features are so delicate that he looks like he might even weigh less than Elizabeth Bennet. Less sex god, more Lib Dem MP.

The portrait, painted by the English miniaturist George Engleheart in 1798 two years after Lefroy and Austen were forced to part because his family didn't consider her to be marriage material, will be on sale at the Grosvenor House Art and Antiques Fair next week with an asking price of £50,000. It is one of only two portraits of Lefroy known to exist. Austen was a rector's daughter and still 13 years away from her first success, Sense And Sensibility, so didn't fit the bill.

Lefroy later described his feelings for her as “boyish love”. Just before they separated Austen wrote: “At length the day is come on which I am to flirt my last with Tom Lefroy... My tears flow as I write at the melancholy idea.” Three years later Lefroy married the heiress Mary Paul and had a successful legal career, becoming chief justice of Ireland and dying at 93. He named his eldest daughter Jane - scant compensation for Austen, who never married.

As for the rest of us, they say you should never get too close to your heroes. Sweet-faced Lefroy may prove the point.

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