In a Bind : Designers strut pullovers, dresses and bodysuits in springy fabrics that cling to every last curve.

Stretch it--up, down or sideways--but stretch it. This was the theme of the British designers’ fall 1991 collections shown here over the weekend. Runways were filled with clinging bodysuits, leggings, second-skin shorts, dresses, jackets and trousers in nylon, Lycra, spandex and various springy fabric blends.

From Rifat Ozbek’s brown-and-black zebra-printed bodysuits and Joe-Casley Hayford’s long black tube dress to Liza Bruce’s black nylon suit with fake-fur cuffs and Vivienne Westwood’s gold-emblem printed bodysuits, the London designers sent out collections that would appear to demand hours of aerobics as preliminary preparation for wearing the clothes.

Aware that they could be stretching their point too far for many women, designers such as Helen Storey, Betty Jackson as well as Ozbek and Bruce offered tailored mid-thigh coat dresses over their form-fitting ensembles. This layered look was the leader among wearable ideas from London for fall. The best coat dresses--actually blazer dresses--came from Betty Jackson, and reflected her modern classical approach to design. Caroline Charles showed lipstick-pink coats in barrel and kimono shapes.

Again this season, many London designers showed their continuing fascination with Africa, as well as with the 1960s. Now they’ve added the ‘70s to their list of inspirations, with beads, psychedelic prints and velvet used in abundance. Leather was included in the retro looks, especially the black motorcycle jacket-inspired coats, leather dresses and halters seen in many collections. It’s a look lifted from the streets of London; on and off the runway, the young crowd has rediscovered tight, low-riding black leather pants.

Shaggy shearling and fake fur were also used in many collections, but in a season where the designers seemed to demonstrate an aversion to conventionally woven fabrics, it was vinyl--black or mother of pearl finished--that most noticeably fired their imaginations.

Among newer names to show here this week, the work of Pascale Smets stood out. She formerly worked for Jean Muir--one of London’s best known designers who celebrated her 25 years in fashion this season with a handsome show of refined knits. Smets showed the most wearable take on the stretch theme, including a chic knit dress with spaghetti straps in burgundy rayon and an understated pea-green wool, Angora and nylon shorts suit. These items suggested a way that the ubiquitous stretch look might be digested into the mainstream.

For women who can stretch it, Liza Bruce, an American designer living in London who started out in swimwear, offered the best lean looks. Jewel-tone separates--pullovers, bodysuits, trousers, skirts and jackets--were the core of her collection. Her short-legged black bodysuit with black voile shoulders was a frisky design for customers who are neither rock stars nor aerobic instructors.

Helen Storey, daughter of playwright David Storey, showed her collection on models masked by wild animal heads like those seen in children’s fairy tales. Her fall styles represented some of the freshest ideas of the season. She opened her show with a black vinyl bodysuit worn with a red velvet cape with a shaggy mouton collar.

Chiffon blouses had braided trim on the sleeves, a black stretch mini had hemline-length black leather lapels, a black velvet dress had a Lycra back and snaps instead of buttons up the side. Storey’s evening wear has always been adventuresome; this season she offered a white Lycra dress with a neckline scooped to the navel, worn over a matching beaded bra.

In the ethnic panoply that London fashion has become, Turkey-born Rifat Ozbek had a Miss Marple-goes-to-Africa theme, teaming sweater sets with African blanket skirts as his main theme this season.

Closer to home, Vivienne Westwood’s models wore Beefeater bear hats as accessories to tight, perforated black leather dresses. Spider-web leggings over stockings and a huge leopard-printed hat with long tails worn as a stole were signs of Westwood’s free and fertile imagination.

As always, there were some quieter items from Westwood that would look good on anyone--well-cut black velvet suits with fake-fur cuffs, raincoats with a colored cherub print and intricately crocheted sweaters and camisoles

Joe Casley-Hayford’s collection had a French ‘50s feel to it. He worked in neon colors and leather, showing tight black leather dresses with vertical belt buckles sewn on the front, and leather dresses with suits-of-cards appliques. Brown velvet pants had cutouts in the back of the leg.

Off the runway, this London season was shadowed by uncertainty about the future of British fashion. Fewer designers staged shows this season.

Glaringly absent was Jasper Conran, one of the most talented London designers. He has signed a manufacturing and distribution agreement with Biederman, the French clothing manufacturer. His absence left many to wonder whether he will show in Paris, as do Katharine Hamnett and John Galliano. Many in London see the trend as undermining London’s fashion vitality. This season, for the first time, Vivienne Westwood will show in Paris as well as London, where she presented her clothing over afternoon tea instead of in a runway show.

Loathing the London Fashion Week’s former location at the dreary Olympia convention center, Katharine Hamnett, perhaps Britain’s best-known designer internationally, advocated moving the shows to Kings Road in Chelsea. That was several seasons ago. When her plan failed, she defected to Paris. This season the shows did move to Kings Road, but Hamnett chose not to take part. “Rather than spending all that money on shows in London, the British Fashion Council should get itself a press office in Paris and move in on the exposition there,” she said.

Ironically, as the London shows have become better organized, many American buyers who attended said they were disappointed in the London collections. This was especially true of those in search of the avant garde. “There was absolutely no new talent this season, “ complained Capu, who buys for Untitled, a New York boutique featuring London designers. “We come to London for young funky designers, and this year it was a waste of time.”

“By changing the venue and creating a polished European look, London has lost the eccentric energy that made it a force on the world stage of fashion,” said Guiseppina di Camillo, a London-based designer who chose not to exhibit on Kings Road.

The annual sales of British designers’ signature collections, along with their lower priced, mass-produced diffusion lines, reached about $500 million last year, compared to $3.5 billion for Italy, $3 billion for France and $1.5 billion for Germany. Clearly, London is not as important a fashion capital as it was in the ‘60s, and has been on and off since then. But with its excellent fashion schools and thriving youth culture, fashion observers believe it will remain a major creative center.