The king of underwear is being deposed and Ralph Lauren is pretender to the throne
How ungrateful the fashion industry can be. In 1982, Calvin Klein began his crusade to save modern women from the horrors of men's underwear. With the help of photographer Bruce Weber, well-endowed Olympic pole vaulter Tom Hintinaus and a 40ft by 50ft billboard above Time Square, Klein declared war on the twilight zone of baggy, greying Y-fronts. By the time Marky Mark was flashing his Calvin waistband under low-slung jeans in 1992, even men had to admit that a pair of "tight whites" by Calvin spelt sex. And now, they tell me, Calvin isn't cool any more.

So, is it back to the novelty boxer shorts then, guys? No, the problem with Calvin started when he sold his $85 million per annum underwear division to Warnaco in 1994. Now they are selling in Tesco at knock-down prices. Then there are the rivals - Ralph Lauren, Valentino, Dolce e Gabbana, Helmut Lang and Yves Saint Laurent - who want a piece of the underwear action.

Graham Haines, owner of the Covent Garden shop Sports Locker, says, "Calvin was our biggest seller but there has been a significant downturn in sales. I predict Polo underwear, which came in about two weeks ago, will take over." The secret of Ralph's success is a mesh "coolmax" panel on the crotch (from pounds 19.99, through which your "profile is exhibited", as Haines delicately puts it). "Packaging and presentation are everything," he says, "and I'm not talking about the box."

Men do buy their own underwear in the Nineties. Calvinism has made designer kegs the rule not the exception. As Hom spokeswoman Sue Loder says, "It may be slightly naff to wear designer logos on the outside, so designer under wear is a discreet form of label snobbery." But it is still sex that sells underwear for pounds 20 a pop. And nobody does it like Calvin and his white, ribbed, high-cut brief (pounds 12.99).

The Full Monty was a hit because it lined up old, young, fat, thin, gay and straight in red satin G-strings. It seemed to be saying that homoeroticism is in the eye of the beholder. If we thought we had to have perfect pectorals and a six-pack like the guys in the ads, we'd still be buying undies from M&S. So, is it the perfect male body in Calvin adverts that we are turning our backs on rather than the product?

You just have to look at the latest billboard ads for Yves Saint Laurent and Polo Ralph Lauren to see that this is not the case. YSL underwear, launched in 1994, is modelled on a powerful, chiselled male body and cut to the classic swimwear contours of the Thirties Riviera look. YSL's Christopher Everard says, "Calvins are more provocatively cut. YSL is still body-conscious but in better quality cotton-jersey swim shapes rather than thigh-skimming briefs."

The YSL trunk (from pounds 14.50) is cut to the contours of the thigh, buttock and crotch with seaming that gives a whole new meaning to Y-front. The same could be said for Polo Ralph Lauren's locker-room briefs. Both have logo'd waist bands that act like elastic corsets to hold you in at the right places. The trend seems to be towards more sports-inspired lines.

But whether you buy Yves, Ralph, or Calvin - and don't let anyone tell you Calvin Klein is not cool - the bottom line is body-consciousness. As fashion writer Colin McDowell says in The Man of Fashion, "the sensuality of such underwear is not meant to be enjoyed by the wearer alone".