There are some trends that are timeless, and the BLJ is one of them. But don't think sweaty; bikers, think Gucci and Prada, says James Sherwood
Conscientious objectors always use "Seen it all before" as a reason to opt out of the fashion system. Steam would come out of every orifice were Style Police to herald the return of something as ubiquitous as the black leather jacket. You can feel the indignation boil at the thought of something so generic being reinvented. Who, after all, hasn't got a BLJ? But let's put it this way. How many Skoda drivers when offered a new Porsche are going to say, "I've already got a car"? Same thing.

Fact. The black leather jacket is the key piece for winter 1999. Clever little devils, these fashion designers. They may fall in love again with black leather but they tweak it sufficiently to make the old models obsolete. Once ubiquitous Chrome Hearts black leather blousons now belong only in the most demode gay clubs and vintage Wham! videos. What we're seeing now is the slim, single-breasted BLJ, the tight, contour-hugging zip- front and the knee-length frockcoat cut working this season. BLJs are multiplying on British streets faster than the flu epidemic.

"Black leather is always going to work because it says sex and it is slimming. It's a light enough fabric to make the cross-over into spring/summer and it is that little bit expensive which makes it a luxury," says Alison Fitzpatrick, deputy fashion editor of Scene. "By hooking into the rustic, bohemian feeling, leather was ready for a revival this season. It is accessible because every generation knows the BLJ is a safe, easy and familiar piece for people to buy." It's like your oldest friend turning up on your doorstep with a fabulous facelift. You want one too.

The kernel of a trend often germinates on the catwalk, then snowballs when the high street gets it, the public loves it and everyone can access it. But that's not enough to make it the people's choice. If Gucci loves and updates it, Noel and Liam wear Seventies retro versions, the mags endorse it and there are many mutations in silhouette, then you've got a winner.

Faycal Amor, design director of Plein Sud, is the designer who put all of his authority behind the BLJ and really led the winter 1999 revival. "For me, leather is indispensable in any collection," says Amor. His collection, a homage to a techno Mata Hari (read urban, dynamic, dressed to kill), ingeniously cut the softest black glove leather into second-skin side- zip jackets and languid aviator coats.

"New technology - for example, hand-waxing and polishing treatments - breathes new life into leather," says Amor. "I made signature pieces only in black leather for winter. Constructivist, architectural shapes for leather are the way forward."

Designers who believed in the BLJ are sufficiently diverse to make the trend far-reaching: Gucci, Herve Leger, Prada, Alexander McQueen and Faycal Amor for Plein Sud supply the sharp, high-design-buying public.

The subversive young Paris school - Veronique Branquinho, Olivier Theyskens and Martin Margiela - gave black leather a futuristic Goth appeal. Kookai, French Connection, Karen Millen, Whistles and Agnes b opened it up to top-end high street.

The successful return of the BLJ works like a fashion John the Baptist. It is heralding the continuing trend for leather which will take us through spring/summer. In a way, the BLJ is softening us up, preparing us for a leather-lined spring/ summer season.

Black is just the beginning. Plein Sud has softened up leather in palest lilac, pearl grey and opal. Prada is peddling punched leather in dull mustard and McQueen worked it in white. But the bottom line is the BLJ will not be redundant come next season. That's the final piece to a powerhouse trend. These leathers aren't going away any time soon.