It's so easy to carp, isn't it? The blogosphere is already thrumming with suggestions that Inès de La Fressange, one-time muse to Karl Lagerfeld, occasional designer and now spokesperson for Roger Vivier, might not be the worthiest recipient ever of the Légion d'honneur, which will be pinned on to her whippet-thin torso in Paris next week. Honestly, what do these detractors want? The Légion d'honneur may have been instituted in 1802 by Napoleon Bonaparte as the highest honour the Republic could bestow. It may sound scarily portentous and look magnificently important: a sort of hybrid between the Victoria Cross and one of those gorgeous enamel flowers that you can get at Dior, although, sadly, without the diamonds. But it is not, repeat not, the Gallic answer to the Nobel Prize. So give Inès a break, OK?

So Inès, with her outstanding services to looking thoroughly damn stylish in an utterly inimitable French way is a more than deserving candidate. Plus, she's 50. This detail is important because de la Fressange is wearing her age in a way that seems possible only in France, which is to say, she's not trying to look as though she's 30. “Thirty?” snorted de la Fressange when we met recently. “A lot of women stick with that because it was their favourite age for some reason. I don't really think like that. I mean, when a man tells you you look good, it's not because you don't have any wrinkles.”

The ageing process is greatly helped when you're tall, thin and look a bit like a boy, albeit one with excellent hair, because let's face it, there's simply less of you to go south/downhill/wrong. So I actually believe her when she says she's reasonably relaxed about getting older, partly because she doesn't appear to have had any work done, and partly because age doesn't seem to be compromising her taste in clothes and accessories at all.

“That's not quite true,” ripostes de la Fressange in her perfect, idiomatic English. “I can't wear really short shorts any more, or fluorescents. Actually, I'm a bit of a navy jumper maniac now. But I'd certainly never go to a shop for 50-year-old women. And I wouldn't go really classic - it's very ageing.” This from the woman who used to live in Chanel, before Lagerfeld unceremoniously fired her as the house's face. But that was when she was still in her twenties, and even then she would mix her tweeds with T-shirts and jeans. Standard practice now, this was considered une vraie scandale at the time.

In retrospect, she says, the 1980s were uptight and heavy, and that living in red lipstick and pearl earrings the size of cupcakes was not her best look. But she thinks in some ways fashion was easier then than now. “There was more to hide behind. Now you have to have perfect skin and amazing hair, because it can't be too dressed. And clean teeth. A lot of women forget about that.” She breaks off as two blonde Russians, a mother and daughter, or maybe a granny and daughter (there isn't a wrinkle between them so it's impossible to be sure), glide past in a haze of perfume and diamonds. “There's also a lot of fun to be had if you are not afraid. It's great to have a beautiful bag,” she says, stroking her patent Vivier, “but I also go everywhere with this plastic sack. You have to mix genres now: if you are wearing an army-surplus coat, put it with ballet shoes, not heavy boots. If you are in diamonds, then play them down with a matelot top. Oh, and never wear fur.” It would be nice to think that this final nugget springs from a well of animal compassion, but I think it has more to do with the fact that fur is bourgeois and ageing. Well, what do you want? She is French.

The style gospel according to Inès de la Fressange

Keep an element of punk in your wardrobe - always. Even Chanel was a bit punk; the way she wore jersey and fake jewellery was a rebellion in her day.

Don't be afraid to make mistakes. If you have never put a foot wrong, you're probably too set in your ways.

Look for alternative ways of expressing what you feel: you may not want to wear a fluorescent dress, but how about a pair of tangerine patent shoes?

Dressing head-to-toe in expensive clothes can be as big a mistake as always wearing cheap ones. At every age it's far more effective to mix things up. I like it best when it's not obvious where my clothes come from.

Be open-minded about new labels. It's great to have tried-and-tested ones, but thanks to my two daughters I'm also a regular at H&M, Gap, Isabel Marant, Aspesi and Vanessa Bruno.

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