It's odd that the perfect white shirt should be so hard to find. Walk into any high street chain and there are lots of them - it's just that to the picky eye there's something just a little bit wrong with most of them.

Doing something simple well isn't easy. Everything needs to come together: it needs fine cotton neither too thin nor too thick, a brilliant cut, great stitching, good buttons, perfect cuffs and sleeve length; and on top of all that, the best require a bit of flair. Which is why, if you were to do the white shirt equivalent of a blind wine tasting - that is, line up a big range with the labels ripped out - you'd nearly always find that the ones you really, really lusted after were made by the masters: Yohji Yamamoto, Comme des Garçons, Jil Sander in the old days, Martin Margiela, Viktor & Rolf (I still lust after one of theirs that I failed to buy a few seasons ago - simple but with an asymmetrical cross-over front and a gorgeous collar). You don't need telling that none of these come cheap.

Whenever I think of the perfect white shirt, I always think of that lanky aristocratic French model, Inès de la Fressange, the one-time muse of Karl Lagerfeld, who had a way with white shirts - although, if you had a face and a figure like hers, it would be hard not to. She wore them strict and straight; on her they looked classier than any couture number. If you want to see how it's done, check her out on YouTube, where she's wearing one that, atypically, has a few frills, teamed with jeans and heels. That's how it's done if you're a jeans-and-heels kind of girl. She also used to tuck them into pencil skirts - very Miss Moneypenny - and was immediately transformed into the kind of secretary whom every man dreamt of having.

If you're going to do that, you need to find one that is cut slim so that it doesn't bulk out the skirt, and pull it together with a gorgeous big belt. Here the high street chains have come into their own. They may not have the perfection of detail that the starrier masters go in for, but they're a whole lot friendlier on the purse and there are plenty of neatly cut versions around.

If you go online right now at Marks & Spencer, for instance, you could find about ten different examples: for my money, the Autograph version in pure cotton with three-quarter-length sleeves (£25) is much the sassiest. Per Una, not usually my favourite part of the M&S emporium, has a very flattering one with diagonal pintucking on the front and cuffs (£35). Nor, I imagine, do I need to remind you of Zara, which has a very good way with white shirts - there are always at least five different versions in stock, with varying degrees of elaboration, pintucking or frills, all from about £35 to £40 a time.

Speaking personally, not having Mlle de la Fressange's androgynous beauty, I like a bit of a ruffle. All those delicious shirts-cum-blouses that Chloé came out with when Phoebe Philo was at the helm were, as far as I was concerned, the perfect paradigm - pretty without being cloying, as good with jeans as with skirts.

The star this winter, if you want the white ruffled shirt that sums up the season, has to be Givenchy's gorgeous ruffled high-necked beauty; but it costs £920. I often find Anne Fontaine, who does almost nothing but variations on the white-shirt theme, somehow not to my taste, but every now and again she hits the button. This winter there are some good ones that she teams with little black waistcoats for a hint of Asiatic chic.

Other good sources are Gap - at £32 a time, the cotton isn't as luscious as I'd like, but it often has a spot-on style and just now is selling one with a panel of little pleats. Thomas Pink, which mostly does men's shirts (fabulous white-shirt bar, chaps) has come out with some very flattering women's versions - some ruffled, some sleek. I particu-larly love its White Collection Ali shirt, which is cut long (to below the hips) and which comes with a flattering black cummerbund (£125 - available in two weeks). You can check them out at www.thomaspink.com, but the pictures don't do them justice.

Then let me introduce you to Yacco Maricard, which is a small Japanese shop at 10, Kensington Church Street, London W8 (020-7376 9151; www.ym-fashion.co.uk), which always has an infinite variety of exquisitely crisp pin-tucked shirts. They're mostly rather loose and can easily double as jackets. They start at about £65 and go up to £260 for the largest and most elaborately pin-tucked.

And if you're far from the shops, check into www.perfekcija.co.uk, which has lots of great white shirts to suit most shapes and tastes - they're all £75.

It's not enough just to buy them; it matters how you wear them. A less-than-crisp white shirt with a dreary black suit does nothing for anybody. Make them look a bit saucy by turning up the collar and turning back the cuffs. If you're young enough and can get away with it, undo one more button.

Of course, it goes without saying that they should be spankingly clean. Get your laundry techniques sorted if yours aren't (go to www.thelaundress.com and check out “pit” stains if that's your problem - you get a live demonstration on what to do). Starch them if they're crisp cotton and iron them beautifully.

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