American fashion buyers have been nosing around corners in France and Italy for the past few weeks, but London is where they're settling down for some major buying.

The attraction is partly a combination of '60s insouciance, good quality and trends not too far from those of the Paris and Milanese arbiters, but not the least of it is the happy dollar-pound exchange rate that has seen British clothing exports to the U.S. increase by 50 per cent over the last year.

"I go to Paris to see direction and trends," says Jan Wallach, fashion director at Garfinckel's. "But I'm in London to really buy." She also made some store purchases in Paris and Milan.

"These clothes are inexpensive compared to elsewhere," concedes Jerry Solovei of Elizabeth Arden.

For Sara Middleman of Saks Fifth Avenue it's the originality of the individual designers. (I've bought a blouse here that has made the whole stop in London worthwhile," he says, pointing to a heirloom lace-trimmed, white silk crepe de chine style at Marisa Martin.)

Indeed, the London fashion scene is strongly reminiscent of the '60 era when Carnaby Street was king. But with improvements - primarily the quality of the design and of the workmanship.

Most American buyers are confining their views of the English designer collections to the shows of 26 top London designers who own their firms, plus the London collections of 72 manufacturers for designers producing in large volume, plus the few independents, such as Jean Muir, Zandra Rhodes, Bill Gibbs and Bruce Oldfield, who have showings at their own houses.

But at the same times 500 manufacturers of lower-price garments are showing their fall goods in Birmingham and Earls Court.

"In London you can count on more original and innovative style than quality," said Robert Sakowitz, head of the Sakowitz stores in Texas, who was in London to buy the Jean Muir and Zandra Rhodes collections he sells well, but also to scout new resources. (One he added this season was Benny Ong.)

"At the better price level, the French designer never stops over the border of elegance," Sakowitz said. "The English designer can be outlandish with establishment-breaking ideas. But when they work, they are whimsical and wonderful."

All that originality that old Carnaby Street charm, comes largely from the eight top fashion design schools plus colleges of art that turn out about 150 potential designers each year. Encouraged by the interest of the adventuresome boutiques in London, many form their own small firms. They avoid the big experienced businessmen and are helped instead by the small groups they form the selves as businesses that make sure quality products are produced and delivered on time.

"If I design something that the people I work with like, then they put love into it and they produce it the best they can," explained Benny Ong. "Id they don't like it, I try to explain is to they can really get on the track and enjoy producing a good product like I enjoy designing it." Ong, who has a company of seven people, says occasionally others talk him out of making up one of his designs, but usually he wins out.

According to Annette Worsley-Taylor, who has organized the top designing group, the only problem now is that most of the American buyers arrive in London absolutely frazzled from their buying expeditions in Milan and Paris. And although they always buy more, Worsley-Taylor thinks the potential is far greater. For that reason, after the four day-long shows, the designers will for the first time pack up their wares and present their collections on Seventh Avenue designers show their fall designs in two weeks.

While most buyers are passing up the old, conservative British look, the modern interpretations of the British sporting style are clearly a winner here. In Paris Kenzo used classic menswear fabrics for oversized, unlined blazers and baggy pants. In London, Wendy Dagworthy, for example, rounds off the stiff classic look of riding jaclets, jodphurs, vyella shirts and coats with dropped schoiulders, drawstring details and oversized patched pockets, giving a baggier look to it all.

By making her clothes fuller, Dagworthy has had to forfeit the classic British menswear fabrics. "The widths of the fabrics used tradionally are no longer wide enough for me," says Dagworth who has had special tweeds and checks made for her women's and men's designs.

As in Paris, an all-out effort has been made to make all the clothes look the opposite of the strict menswear theme of a year back. Ruffles and lace, pleats and embroidery, in fact anything that undermines a stiff classic look was been put into use.

It's these pretty dresses that make the British designers stand apart from the French, along with the fact designers that they are totally in the current theme of light, loose-fitting clothes.

"Isn't it remarkable that the British who are so unromantic themselves can make such romantic dresses," said Sandra Best, an American who has been designing in London since Carnaby Street days.

Gina Fratini is so sold on ruffles that each time she looks at a favorite "Gone With The Wind" style in chocolate with several tiers of lace, she adds more lace, and an occasional cabbage rose in silk. She's now doing daytime clothes for the first time - "I've always been strictly into fantasy' - because she happened to see some knits that she liked. Among the winners is a full-brown blouson mini tunic to be worn with matching socks over tights. "I said to the pattern marker 'It should be enormous and once you understand that, make it twice that size,'" Fratini explained.

The master knitter is Kay Cosserat who knits loose-shape separates and huge jackets of mohair, sometimes with fake fur woven through to enhance the textured look.

Apparently it is not only luxury but a ritzy look that is appealing this season. Many of the fabrics are shot through with gold.

"These are not precious clothes, but for mums and daughters to wear who want pratical clothes," said designer Gordon L. Clarke, looking at the ruffled dresses, in the showroom area on each side of his stand. "These clothes aren't fantasties; women should only have fantasties when they take off my clothes, not when they wear them."

Benny Ong, whose current fantasy is Barry Lyndon, says the reason he and others have had such success with evening clothes is that the British like to dress up. "The queen helps," he says, "because you always see her in a long gown.

It was the queen's sister, Princess Margaret, who made the first nod to the British ready-to-wear industry by showing up for lunch and a fashion show with one designer group and making the rounds of another group of designers showing in London. It's the first time anyone can recall that a member of the royal family attened a fashion event of this sort.

One obvious draw for Princess Margaret was the fact that the opening show was pitched to the Jubilee Celebration of the Queen's 25th year since crowded. The opening lunch was a benefit for the queen's Jubilee appeal whose goal is to raise 50 million pounds ($85 million) for youth clubs.