Fashion: A U-turn, as simple as that: When Versace goes minimalist, you know things have changed. Lisa Armstrong reports from Paris, where the couture and the etiquette are both under revision

A new world order is emerging in Paris's gilded salons. Gone are the days of Eighties-style couture, in which all the expensive work was on the outside and no rhinestone was left unturned while there was still a millimetre of dress on which to deposit it. Instead, black and white are now the ruling palette. Simplicity of cut (the kind that wouldn't disgrace a very chic nun) is the order of the day. Stranger things may have happened in the past 40,000 years, but if so no one in Paris this week could recall them: Versace has turned minimalist.

The etiquette of couture is also under revision. For one thing, the fondants, the skinny American socialites who change their pastel outfits four times a day (although in the 90 degree heat they still look like melting sorbets) are now wearing trousers. Not long ago this would have been inconceivable. Fondants like their legs (they paid enough for them) but fashion - in Paris at least - is at sixes and sevens over the great hemline debate, so pants it must be.

Once couture would have resolved such issues as skirt lengths with one icy diktat. No more. This autumn, couturiers backed the longer skirt (with the glaring exception of Gianfranco Ferre, who stubbornly kept his three inches above the knee at Dior, and decorated them with pompoms of dyed mink) but they couldn't decide how long or what shape. At Valentino they hit just below the knee.

And confusingly Versace, who last year declared that he hated long, produced skinny ankle-length tubes while Karl Lagerfeld, who was one of the first to embrace long, raised his skirts to just below the knee and gathered them into folds (the most wearable option to emerge all week). There was stronger unanimity over trousers, which (to the chagrin of the fondants, who were in narrow) were nearly all wide, with skinny tops or mid- thigh-length jackets.

Seventies retro vision was another common thread. One thing was

universal - impossibly high platform shoes. When Claudia wasn't tripping over them at Valentino, Naomi was nearly breaking her neck in them at Versace. At last these girls were visibly earning their money. But back to the politesse of couture. For trousers are not the only new visitation to the front row. Walkers - those male chaperones who accompanied the Eighties fondant on her social round while her busy husband asset-stripped a few more companies - have been ousted by children.

Ivana Trump sat in the front row with her 10-year-old Versace-clad daughter, Ivanka. Across the way sat Mrs Hirsch, wife of a German industrialist, with a dazed-looking son clamped tightly to her lap. Every time the photographers gathered, the four gleaming blondes (Mrs Hirsch reputedly dyes her son's hair to match hers) posed in loving harmony. And when the lights dimmed, Mrs Hirsch spent the next 45 minutes ignoring the clothes on the catwalk and concentrated on who was looking at her.

And therein lies the rub. For the other shift in couture politics is that the glamorous, wealthy socialites who were heralded as the saviours of couture five years ago are now content to treat the shows purely as social events. It is no longer deemed tacky to attend without buying. The cost of couture remains sky-high ( pounds 20,000 upwards for an evening dress) despite the complaint of Pierre Berge, the head of Yves Saint Laurent, last season that prices were 20 to 30 per cent too high. Consequently, purchasing power is slipping back to Middle Eastern customers. Not for nothing were several shows delayed - despite the ostensible guests of honour being in place - until silent caravans of veiled women had been discreetly ushered to their seats, away from the glare at the front, in the third or fourth row. It would be ironical if, having finally modernised itself to the point where it is simple and purged of excessive glitz, couture reverted to its rhinestone-studded past to keep its new client base happy.

Still, some things remain reassuringly constant. Paranoia still rules. The gilt chairs with their little handwritten tags are still there. So are the coded messages. If you think a show was unwearable, you say it was 'directional'. If you found it vulgar, you describe it as 'exuberant'. And if it worked on your nervous system faster than valium, you pronounce it 'classic'. This is because if you are a customer you do not wish to appear old- fashioned. And if you are in magazines you don't want to offend a designer and jeopardise advertising. If you are in American fashion magazines you are doubly nervous, because where there was one Queen Bee there are now two: Anna Wintour, editor of US Vogue and Liz Tilberis, editor of Harper's Bazaar. Both sport complementing power bobs and British accents. But the cameraderie ends there, for both are determined to produce The Best Fashion Magazine Ever and they are prepared to woo each other's photographers, writers and readers to do so. With three weeks to go before the launch of the new Harper's, there were times this week when Paris didn't seem big enough for the both of them.

Things were dicey backstage, too. There were rumours of a rift at Saint Laurent over Berge's backing for his protege, Robert Merloz, a young designer who launched a collection this week and was roasted in the press. This led to Yves Saint Laurent's mother breaking a couture golden rule: she told the truth and pronounced the collection mediocre.

However, couture is about beautiful clothes, and there were plenty. At Lacroix, wonderful fitted jackets flared out over the waist in full peplums, fabulous long cashmere redingotes were crowned with buttons the size of saucers, and adorable patchwork cardigans payed chic homage to the Seventies. Lacroix knows how to produce couture that looks like couture - his velvet hippy dresses were smothered with discs of beaten gold but because they were witty, rarely looked vulgar.

Ferre on the other hand seems overwhelmed by couture. He can produce stylish, restrained trouser suits but all too frequently some other force grips him. He remembers that couture is supposed to look expensive and out comes a succession of five- mile-long trains and tortured ideas (latest one is a full black short dress flipped up at the hem to reveal layers of stiffened petticoats that look like an Elizabethan ruff).

At his most excessive, Ferre illustrated where the future of couture does not lie: in grand occasion wear that no one has the occasion to wear.

Valentino rarely falls into this trap. His workmanship is exquisite, but his Forties starlet inspired daywear - strict, slim and curvy, with skirts falling to below the knee and often ending in a fluted hem or shower of kick pleats - was eminently wearable. His chiffon evening gowns with bodices made out of plaited satin ribbons were extremely clever without making a song and dance about it.

Even Ungaro, the man to whom the euphemism 'exuberant' is most frequently applied, has caught on to the new puritanism. Gone were the swags, bustles and 12- different-prints-in-one-outfit extravaganzas. In their place were black velvet sheaths that hugged every pore. Ungaro being Ungaro, these were heavily festooned with jet, lace and his trademark - embroidered roses. But without the billowing taffeta it was possible to see what a superb cutter and fitter he is.

Couture is not designed to make money but to generate publicity and thereby increase perfume and ready-to-wear sales. That does not mean it should not be wearable as well as experimental. Lagerfeld and Versace know this. They set a mood (Seventies at Versace; Seventies and the 18th century at Chanel) and exploited it to produce the mad but inspiring as well as the eminently commercial. Mad at Chanel included plunging velvet corset dresses with ruched woollen skirts (this was the 18th century not of Marie Antoinette but of the sans-culottes; with breathtaking irony Lagerfeld took the finest wools and spun them into dusty-coloured gauzes that looked like the sort of thing a serving wench might wear). We had seen these looks before - at Westwood and Galliano - but he made them accessible. Commercial included highly desirable fine wool black wide pants and mid-thigh cardigan jackets teamed with floppy velvet hats and knee-length necklaces. It was relaxed, amusing and very chic.

Versace's frivolity was confined to half a dozen overblown ball gowns. The rest of the time he stuck to three colours (black, lime and orange), two fabrics (crepe and leather) and stark, sinuous shapes. Skirts were snaky and long, dresses were immaculate sheaths or gently flared from below the bust. Jackets curved and trousers sprouted the sharpest bell-bottoms in town.

Anyone who has dismissed Versace as too much should think again - this was a tour de force of simplicity (though there was nothing simple about its execution). In ditching his signature prints and panniers, Versace perpetrated the biggest U-turn since George Bush broke his 'no new taxes' pledge. Versace's volte-face was ecstatically received. Come November, Bush should be so lucky.