Rebecca Tyrrel: 'Keira Knightley could do for Imelda Marcos what Meryl Streep did for Mrs Thatcher'

Who knew that if Keira Knightley 'adores' a pair of shoes she sees in a shop, she will buy them whether they are available in her size or not?

Students of red-carpet photography will have noticed considerable heel-gape (the gap at the back if you step into shoes that are too big for you) in shots of the winsome young actress. Indeed, so capacious is some of her footwear that you could fit a whole extra Keira into the chasm.

Shoes are not the only commodities that are sometimes too big for Miss Knightley. Her dresses have been known to gape enough for us to count her ribs, while critics have suspected her of being swamped by her film parts. From the 18th-century portraits of her, Georgiana, Duchess of Devonshire looks a shade stout for our adorable little waif, while Elizabeth Bennet was possibly more bonny than bony to Jane Austen's mind. This is absolutely not a comment on Keira's acting ability, merely a musing on how a pretty, pouting girl with an emphatic jawline carries off an empire-line dress.

But back to the footwear. Billy Bob Thornton, who as an OCD sufferer himself must be listened to on the point, has observed that, "When people wear shoes that don't fit them, it says something about their soul" (though, given that this was a verbal quote what he might have said was "it says something about their sole"). On the other hand, some regard ill-fitting footwear as a sign less of psychic pain than moral strength.

"I would hate for someone to look at my shoe and say, 'Oh my God! That looks so comfortable'," declares Christian Louboutin, the world's most fêted shoe designer, a favourite of Victoria Beckham and Coleen Rooney. "Comfort is not part of my creative process." Meanwhile, the late Beryl Bainbridge compared uncomfortable shoes to being constantly with small children... irritating and often painful, but ultimately rewarding. She couldn't bear to throw out a pair, even if it gave her blisters.

And back to Keira, who would be cast against type as Cinderella (of the perfectly-fitting glass slipper) but who, when Hollywood finally gets round to it, could do for Imelda Marcos – someone who saw shoe collecting as "a symbol of thanksgiving and love" – what Meryl Streep did for Mrs Thatcher. And God willing there won't be a millimetre of heel-gape when she goes up to collect her Oscar.