When the jockey arrived at Saratoga Race Track today, a battery of television cameras and interviewers met him. When he walked to the paddock before the first race, adoring fans besieged him and pleaded for his autograph. b

It has been like this every time Steve Cauthen comes from England to make a high-priced guest appearance at an American track: He is hailed as a returning hero. These adulatory receptions are, of course, tinged by considerable irony.

When he left this country to complete in Europe, Cauthen had become almost a professional embarrassment. He made headlines for losing races instead of winning them. He had been fired as the rider of Affirmed, the colt who had brought him his greatest fame. In England his success has been moderate; he certainly has not recaptured the form that once made him known as "Stevie Wonder."

Yet despite his mediocre record for the past two years, the Cauthen mystique remains unblemished. The best jockeys in America can ply their trade here daily, while being ignored by the media and periodically booed by the fans. Cauthen is winless on four rides today and still seems larger than life.

The season, in part, is that he once was a genuine superstar. In 1977, his first full season in New York, Cauthen possessed a special, undefinable magic as a jockey. Even the most cynical horseplayers conceded that he seemed to possess a mystical ability to improve the animals he rode -- and almost to transform their very nature.

He was not only a riding prodigy; he was the Great White Hope. The great jockeys in New York were tough, cliquish Latins. Now a fuss-faced teen-ager had come into their midst, in the media center of the nation, and was beating them while charming everybody else.

But by mid-1978, after he had reached the zenith of stardom by winning the Triple Crown aboard Affirmed, the magic suddenly deserted him. At Saratoga in 1978 he was riding dismally. When a horse was left at the post grizzled bettors would say reflexively, "That must be Cauthen" and when they looked at their programs they usually saw that it was. By the end of the year Cauthen's woes became a subject of nationwide attention as he rode 110 straight losers in California.

What happened? The explanations abound: Cauthen was adversely affected by a couple of spills on the track. His agent wasn't getting him good mounts any more. He had discovered girls.

"People look for all kinds of psychological explanations for his slump," said Cauthen's biographer, Pete Axthelm, "but the reason may be simpler than that: He grew. He'd always been in perfect tune with a horse, and then he grew several inches and put on several pounds." In the process, the magical chemistry may have been altered.

Gamblers can understand better than most people, something else that probably happened to Cauthen. When anybody enjoys the kind of success that Cauthen did in 1977 he gets a sense of self confidence that breeds more success. And failure subtly breeds attitudes that produce more failure. When that happens, and a man finds himself mired in a losing streak, he is apt to look for a fresh start. Cauthen got it when owner Robert Sangster offered him a rich contract to ride for his stable in Europe.

The change obviously has benefited Cauthen as a person. He no longer is the shy youngster from the backwoods of Kentucky. He arrived in Saragota today, impeccably tailored and addressed his interviewers in a voice that sounded more London than Louisville. While he still retains the soft-spoken charm that made him everybody's darling in 1977, he has acquired poise, self-assurance, articulateness. Steve Cauthen is no longer "The Kid."

He talks about his European venture as a great challenge and learning experience. "The races are run a lot differently and the horses are trained a lot differently, and it takes a while to get used to the racing there," he said. "Here it's important to get out of the gate quickly and save ground.In Europe the pace is a lot slower and the tactics are a lot different. The straight's (stretches) there are five furlongs long and you can't be going to the lead too early. I've improved a lot from last year to this. Now I can be called an international rider."

But if Cauthen has developed a wider range of skills, his achievements abroad have not been exceptional. He has been riding for Sangster's second-string European stable, and has not had the assignment on many top-notch horses. He has won with 43 of 321 mounts this year, but none of his victories has come in a major race.

One English observer who was initially a big Cauthen booster said that his riding form has deteriorated markedly in the last few months. And when he has ridden on "Steve Cauthen Day" at various American tracks, his performance often have been poor.

But if Cauthen knows or worries that he has lost the magic, he doesn't reveal it -- either publicly or privately. When he was at the peak of his career, friends said he seemed utterly unaffected by his success. And when he endured his 110-race losing streak, he did not seem to be a tortured human being.

Ultimately, though, Cauthen will return to his homeland where he will have to confront the difference between what he is and what he used to be. Some well-informed sources say that he will return to New York next year.

Cauthen denied that report today. "At the moment," he said, "I don't think it's the right time. I'll probably stay in England next year. But when I do come back, I know I'm going to have to prove myself again."