It was probably only a matter of time before Keira Knightley – she of the Princess Diana eyes, the cheese-grater cheekbones and the tremulous, plumped lips – became the muse of the moment.

She’s currently lighting up screens around the country with her Oscar-tipped performance in Atonement, carrying her 1930s silk dresses with a rude elegance.

“For me, Keira embodies perfection itself,” says Jacques Helleu, Chanel’s artistic director, who has just hired her to be the face of Coco Mademoiselle perfume. Like many of the men who fall for her charms – and they are many – he seems blissfully unaware of the hyperbole. “She is remarkable without any kind of decoration. And I thought, if this is how she is bare, then I could imagine how wonderful she would be embellished.”

Knightley fits right in at Chanel. So much so that she is rumoured to have won the part of the late, great Coco Chanel herself, in a biopic of the designer. Coco’s importance to fashion cannot be overstated – sometimes you wonder if she was just a myth, too chic, perhaps, to exist. Knightley’s beauty is almost like that.

Another key to Knightley’s new-muse status is her imperviousness to the pressure to be a style icon. She isn’t Hoxton cool or an LA princess. She is often pictured walking down the street wearing jeans, a nice jacket, a jaunty hat – sort of groovy, but essentially quite square. She could be French.

Could be, if she weren’t plainly so English – a jolly home-counties girl, not unlike Liz Hurley. Hearing her talk is confusing in the same way as when Hurley opens her mouth: there’s an uncomfortable disconnect between the sensuous face and the hockey-team voice.

Cerebral men adore that disconnect: they dream of storming the gauche, posh veneer to find a hot little sex kitten underneath. In Atonement, James McAvoy’s Robbie does just that – he breaks the reserve of Knightley’s brittle Cecilia against the bookshelves in the library. It’s easily the best scene in the film.

The reason that cameras return greedily to Knightley’s face, again and again, is that she has been given a disproportionate slice of nature’s bounty. Obviously, that is unfair. Our challenge – one we are more than capable of meeting, since we are essentially good people in full control of our emotions, even the negative ones – is not to get very, very angry with her for it.

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