Anyone in search of evidence that what has changed over the past 50 years of fashion history is not so much the clothes as the codes, need only compare the WMD (What Would Mother Do?) question that stylish women asked themselves in the 1950s with the question they put to themselves now; What Would Moss or Macpherson Do?

Mother certainly wouldn't have worn shorts for very long past the age of consent. Not ever. Elle Macpherson gets away with them in her 40s. Kate Moss wears them at 34 and shows every sign of intending to wear them when she's 90.

So that's that then. Shorts work at many ages - although with several gazillion caveats. The stakes are high, but so's the pay-out if you get it right. First - and this is not self-hating sexism but common courtesy to the rest of the planet - you have, have, have to have good legs. Alternatively you have to have so much attitude and je ne sais quoi-ishness that you make Beth Ditto seem like the class nerd. Even then, I would be lying if I said shorts would be Beth Ditto's best look. I'm sorry if that seems hurtful, but part of being a fully evolved human being is accepting well-intended dictatorship. Secondly, context is everything. Under no circumstances should a grown-up woman wear shorts in an office or a town - they're just not sufficiently serious. If it's hot and you want to show off your tan, wear a short skirt instead, which, if you're wearing it properly, should look elegant and chic.

Shorts are never elegant. That's not their point. But they can be cute, boyish and strike just the right holiday vibe. That's why I'd advise against overly designed and crisply tailored ones. What's their point? Fortysomethings are better off with a nicely cut pair of denim or cotton shorts that say Cool and in Control of My Sense of Self. Hot-pants aren't advised - too try-hard apart from anything else. Nor is anything too tight or too long, or it stops being a short. Mid-thigh is a good starting point. High waisters, like these from Paul Smith are good for accentuating the waist. Flat sandals are a must. You don't want to look like that tarty blonde one from Desperate Housewives. What you lose in leg length you gain as person. It's hot, but there's no need to abandon dignity.

How old is too old for G-strings?

A guide to the clothes and accessories that do (and don't .This week: underwear

BACKGROUND

• Grown-up fashion: the body makes a comeback

• Grown-up fashion: can older women wear bondage shoes?

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