Hold up! Who's this walking down a New York pavement, dressed in black hoody pulled up over rat's-tail wet hair, visor shades, a diaphanous black vest and scarlet satin bloomers trimmed with black lace, from which protrude pale bare legs shod in a pair of Louis-heeled T-bar shoes, straps unfastened?

Blimey, I dunno. Could be anyone, couldn't it? Well, probably not Plum Sykes or Anna Wintour, but that doesn't really narrow it down much. Er, is it that madwoman from Sex and the City? Yes, I know they're all mad, but you know the one I mean - huge head, tiny body, immense feet. Looks as though she got dressed in the dark when the fire alarm went off. Carrie, that's the one. Not her? Go on, you'd better tell me.

Oh, you're no fun. All right, it's Madonna. And the one thing you can say with absolute certainty about that outfit is that it wasn't styled by anyone other than herself. Now, the truly sad thing about being Madonna's contemporary is that, while one's first thoughts on clocking her trolling down the street in her bright red knickers are a) Ooh, look, no tan. Is that all right, then? b) Gnarled hands, wrinkly knees. Are they all right these days as well? And c) Oh honestly, look at the state of her. How is that a dignified look for a woman a month off her half-century? Straight after that there comes popping into one's head a quite different set of thoughts: unwanted, irrepressible and just plain wrong. Hmm, you find yourself helplessly musing. Red satin bloomers, eh? T-bar shoes. I wonder...

No. Stop it. Really, stop it now. Let's just think for a moment what Trinny and Susannah would do with that outfit if they got their hands on it. Out would come the big scissors and - snip, snap - before Madge knew where she was, she'd find herself in a stout foundation garment and a smart lilac skirt suit from Designers at Debenhams, artfully cut to conceal her strapping thighs and make the best of her magnificent cleavage, with a sparkly corsage detail just to underline the point. So much better! Sarch an improvement! And then, shedding a tear of gratitude - hastily blotted in order not to smudge her discreetly applied foundation concealer blusher mascara and lipgloss, she falls into the arms of her husband, who says, as the husbands of women made over by Susannah and Trinny always sportingly do say: “Blimey, I've never seen her looking like that before.”

Ho. Which brings us back to the question of why Madonna may have thought it a good plan to venture out dressed in red satin drawers and undone shoes. On a superficial level the answer is perfectly obvious. Madonna is the mistress of self-reinvention. We've had waistcoat and flat cap clay-shooting Madonna, I'm a serious equestrienne taking riding lessons with William Fox-Pitt Madonna, and iced fancies at the Ritz and dainty children's stories tea gown Madonna. Understandably she has grown bored with all that Harris tweed and floral crepe de Chine, and fancies a little retrospective of the captivatingly slutty Desperately Seeking Susan style that looked so original back in the mid-Eighties. That's all. Why does everything have to mean something?

Well, because it just does. That's the thing about semiotics. You can't get away from them. If you go walking down the street in underwear and unfastened shoes you are liable to look ... undone. And if you appear in public looking undone while at the same time your spokesman is issuing statements saying that your marriage is absolutely fine, no question of divorce, nor of romantic involvement in any way with Alex Rodriguez, the world's most expensive baseball player, whose wife Cynthia has coincidentally hit him with a £50 million divorce suit just as he has allegedly developed an interest in kabbalah, the mystical Jewish movement in which you also, coincidentally, take an interest, it is not inconceivable that impertinent sartorial semioticians will conclude that your get-up is mutely undermining every word your spokesman has just uttered.

Then again, there is something else going on with that outfit that is neither mere disorder nor Eighties retrospective but a sort of Toulouse-Lautrec-ish Montmartre-in-the1890s vibe ... I know, it's Madonna does Yvette Guilbert.

This May, Madonna appeared on the cover of Vanity Fair in characteristic dominatrix garb - black leotard, studded corset belt, laced thigh boots. Across her knees was stamped the legend “Madonna - unbowed, uncowed, still taking on the world*”. And in teeny-weeny print in the bottom left-hand corner of the cover, next to the answering asterisk, appeared the words “And she's almost 50!”

Dear, oh dear. That asterisk, that tiny print, that degree of being patronised by a mere writer of magazine cover lines when you are one of the most successful performers, male or female, in the world. Does anyone say of George Clooney, as though he were almost 90 and could still remember his own name, “And he's almost 50!” Would it be any wonder if Madonna's thoughts were to drift in the direction of a culture in which women of a certain age are not patronised with asterisks but cherished and desired?

Back to Yvette Guilbert, jolie laide whose long, pale limbs and slightly raddled allure made her a favourite model for Toulouse-Lautrec while her raunchy lyrics scandalised and captivated audiences at the Moulin Rouge. In later life she became rather respectable: performed for Edward VII, took to writing fiction and running schools for young girls, and was awarded the Légion d'honneur. Remind you of anyone? That little rosette of the Légion d'honneur - Kylie has one, you know. So has Barbra Streisand. Such a pretty shade of scarlet. Just the shade of a certain pair of scarlet satin bloomers, now I come to think of it...

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