SYDNEY -- When Gai Smith married Robbie Waterhouse, the wedding made headlines throughout Australia, for it represented a union of two of the country's most prominent racing families.

Gai was the daughter of Tommy Smith, the leading trainer in Sydney for decades, the most venerated member of his profession. Robbie was the son of Bill Waterhouse, the biggest bookmaker in Australia, and the heir to his father's position of preeminence.

The marriage has still been making headlines in recent weeks, but this time they have been decidedly less romantic. A typical one read: NO LICENSE FOR WIFE OF 'CROOK'

The extraordinary legal plight of Gai Smith Waterhouse was the result of the most notorious horse race in Australia's history. A team of conspirators had attempted to execute a nationwide betting coup by substituting a high-class horse for a cheap one named Fine Cotton at a track in Brisbane. But the whole effort was so clumsy, and word of the plot leaked out in so many places, that stewards realized the winning horse was a "ringer" and disqualified him.

A gambler involved in the coup had come to Waterhouse for help in getting down a $40,000 wager, and Waterhouse provided the assistance, while making bets of his own on Fine Cotton. The bookmaker insists that he didn't know or ask what was behind the plunge on Fine Cotton, and this is probably true, because most gamblers would have considered the details irrelevant; the fact that so much well-connected money was moving on behalf of a horse was reason enough to jump on the bandwagon.

Scores of other bettors had done the same, but when the scandal blew up, public attention immediately focused on the Waterhouse link. Bookmakers in Australia have always been magnets for suspicions about larceny; the biggest bookmakers engender the most suspicions. And the rich, arrogant Waterhouses already had plenty of enemies.

The Australian Jockey Club's investigation found no proof that the Waterhouses had been instigators, but the sport's highest body charged the bookmakers with "having prior knowledge" of the coup. This might seem an odd crime, inasmuch as every horse bettor alive has occasionally listened to tales of larceny about an upcoming race and bet accordingly. Journalist Kevin Perkins wrote in his biography of the Waterhouse family, "They brought in a new charge never laid before because they couldn't find any offence under the rules of racing." Robbie sealed his own fate when he denied to the investigators that he had bet on Fine Cotton, and the racing authorities barred both him and his father from the sport.

While this was professionally devastating for the bookmakers, it was also personally devastating to Robbie and Gai. They had been the most prominent and glamorous couple in the sport. Now Gai couldn't be seen in racing circles with her husband and, wherever she went, she would hear the whispers behind her back.

Gai Smith had left her native Australia to become an actress in England, but her father persuaded her to return home to the horse business. She continued to work in media -- she met Robbie when she interviewed him on a TV racing program -- but she immersed herself in the tough day-to-day work of her father's business. She goes to the track at 4 in the morning, preparing horses for their morning activity; she runs the stable when her father is overseas; she accompanies their top horses to out-of-town stakes races. All of this constituted her preparation to take over from her father when he retires. Last September Gai applied for her trainer's license, which should have been a formality for anyone with her credentials.

The Australian Jockey Club turned down her application -- on the grounds that she is Robbie Waterhouse's wife.

"There are one or two people on the committee who obviously have very strong feelings about us and are determined to keep us out at whatever cost," she said. "When they knocked me back I went to my lawyer and asked what was the best avenue for us to pursue." The attorney took Gai Smith Waterhouse's case to Australia's Equal Opportunity Tribunal, arguing that this was sex discrimination to deny her a career because of her husband's identity. The hearing was a cause celebre for days.

Racing authorities argued that it would be wrong to give a license to Gai when she was susceptible to influence from her husband. An executive of the Australian Jockey Club testified that Robbie Waterhouse was "a deceitful man who had a commanding personality and a capacity to influence others. It would be a joke to give a license to Gai Waterhouse in circumstances where Robbie Waterhouse . . . was in a position to influence her." Gai's lawyer countered that this was a "most appalling" denial of justice because her own merits and character had never been considered.

Gai's plight evoked sympathy from the public as well as from the Equal Opportunity Tribunal, whose chairman said the presumption that a wife would be under the influence of her husband "is the kind of stereotyping which the Anti-Discrimination Act seeks to eliminate."

Nevertheless, the tribunal ruled in favor of the Australian Jockey Club and against Gai Smith Waterhouse, citing both legal precedent and logic. In another sex-discrimination case, a jurist had observed, "I do not think that the law would prevent an employer refusing to engage as a live-in cook a man who was cohabiting with Typhoid Mary."

That is the way the Waterhouses continue to be viewed by the racing authorities: as a poisonous influence ready to infect the sport with corruption. And because of that perception, the woman who might become the world's most successful horse trainer of her sex may never get her chance.