Only a year ago, news accounts were once again proclaiming that the storied romance of Prince Charles and Princess Diana was showing continued signs of premature aging. Their marriage was dissected daily by the tabloid press, and their every movement was the subject of relentless public speculation. So distressed was Diana that she sought comfort and counsel from someone in her life who provided unconditional support—her mother, Frances Shand Kydd.

Now Frances, 52, might like the favor returned. Last week in London she announced that her 19-year marriage to wallpaper baron Peter Shand Kydd, 63, was over. In a brief statement issued by her lawyer, she said, "I would like it known that my husband and I have separated. This is a great sadness for us both. No one else is involved and neither Peter nor I will be making any further comment."

She was true to her word. Callers at her Seil Island home off Scotland's west coast were intercepted by a lodgekeeper and turned away. But newspapers were more than happy to fill the information void. The News of the World claimed that Peter wants to return to his first wife, Janet, an artist and antiques dealer in Chelsea. (A friend of Janet's dismissed the report as "completely untrue.") A second scenario laid the blame for the split on Peter's alleged fondness for alcohol. "He liked a tipple," a neighbor was quoted as saying. "Every time I met him, he would have a drink in his hand. I never saw him staggering or falling over, but he could knock it back."

Whatever the reason for the separation, it came as no surprise to Diana. "She's so close to her mother, she would have long been aware of the problems," says a palace insider. Even casual observers sensed that something was wrong. "We've been wondering for some time if everything was well with the marriage," admitted a resident of the Scottish town of Oban, where Frances owns a card shop. "Mr. Shand Kydd has hardly ever been seen in Oban. And you could count on the fingers of one hand the number of times they have been out as a couple."

A divorce is possible, but without the stir that preceded the Shand Kydds' marriage in 1969. Peter was a suave and lively former Royal Navy officer when he met Frances at a fashionable London dinner party in 1966. Frances, apparently disenchanted with quiet (some would say uninspiring) Johnnie Spencer, then Lord Althorp, was soon smitten. An affair began, and Frances moved to an apartment, a decision that came "like a thunderbolt" to her husband, he once said. Janet Shand Kydd won an uncontested divorce and custody of their three children.

But between the Spencers, there followed a rancorous custody battle for Diana and her three siblings. Lord Althorp eventually won his case, but the bitterness between him and Frances took a great toll on their children—Sarah, then 12, Jane, 10, Charles, 3, and especially Diana, who was 6 at the time and devastated. "I'll never marry unless I really love, really love, someone," the Daily Mail says Diana once told her favorite nanny. "If you're not really sure you love someone, then you might get divorced."

For her indiscretion, Frances paid a large social price. Her behavior, particularly coming from someone so close to the royal family, was regarded as scandalous. (Her mother, Ruth Lady Fermoy, is Woman of the Bedchamber to the Queen Mother; Lord Althorp was an equerry to King George VI and later aide-de-camp to Queen Elizabeth.) She was pilloried by the press and ostracized by the aristocracy.

As a result, she and Peter, who married quietly in 1969 after her divorce became final, lived in a kind of self-imposed exile, dividing their time between their sheep farm in Australia and their remote 1,000-acre spread in Scotland. Her children visited on holidays, which were spent in London or at one of Frances' country homes.

Values, like the times, have changed. To be sure, revelations such as those involving the Duchess of York's unfortunate father, Ronald Ferguson, who was caught leaving a London sex parlor, still raise the royal blood pressure. But the end of a marriage elicits no more than a collective sigh. Some say that the aristocratic establishment would be delighted to forgive the Prince of Wales's mother-in-law and take her once more to its bosom, but it is an invitation Frances is unlikely to accept. "She really wants nothing to do with them at all," says one palace watcher. "She doesn't want to know the people who treated her so badly."

—By Bonnie Johnson, with Terry Smith in London