Haunted by a final rift with Diana Profile: Frances Shand Kydd. As Diana's mother gave testimony in the trial of Paul Burrell, her tranquil island home was burgled. For a vulnerable woman, alone and beset by troubles in her later years, it was just a

Looking fragile, and older than her 66 years, this week she made a rare public appearance in London at the trial of Princess Diana's former butler. There, she admitted to a four-month silence between herself and youngest daughter following a bitter fall-out. So deep was the upset between the two that the princess sent several of her mother's letters back unopened. Tragically, there was no warm reconciliation or forgiving phone call before the accident which killed Diana and separated them forever, a fact which haunts the bereaved mother. Neither was Mrs Shand Kydd able to see the body of her daughter before the funeral to say a private goodbye.

Though the adult Spencer children - Lady Sarah, Lady Jane, and Earl Spencer - remain in the shadow of their lost sister, spending much of their time managing her memorial fund and running the grounds at the family estate at Althorp, where she is buried, none seems as visibly wounded by the events of the past as Diana's mother. That pain was clear to be seen as she gave evidence for the prosecution at the trial of Paul Burrell, the butler who denies stealing 310 items from the princess, Prince William, and Prince Charles. As revelations of the family row emerged, she stood in the witness box, leaning heavily on a walking stick, and clutching a crucifix in her left hand.

During two hours of questioning, she said she and her daughter had been estranged before the fatal accident. She also disputed claims by Burrell that he had been asked to keep certain of Diana's possessions safe. While strongly denying the family fight was over her disapproval of Diana's boyfriend, Dodi al Fayed, she did not offer another explanation. Royal watchers believe, however, the cause of Diana's anger may have been an article done for charity in Hello! magazine, in which her mother revealed that Diana had not minded losing the title HRH and openly discussed her bulimia.

Forced by the Old Bailey to discuss the rift in public, it is unlikely that Mrs Shand Kydd will ever talk again about her dispute with Diana. Meanwhile, in a cruel twist, which, perhaps, highlights her vulnerability, as she stood in court her island home was burgled. The jewellery collection she had owned all her life was taken.

Over the years Mrs Shand Kydd has tried to cope with loss in her own way. She converted to Roman Catholicism eight years ago and has said that she would never place blame or anger over the details of her daughter's death, as there would be little point. ''When Diana died, it was wonderful being a Catholic. I believe that a child is a gift. God can take that gift away without reproach or question,'' she explained.

After the accident, she was surprised to find she was still an executor of her daughter's (pounds) 21m will, and was given special responsibility for overseeing the raising of the Princes William and Harry. Prince Charles is said to admire the dignity and strength she has shown, and is grateful for her efforts in ensuring the privacy of his sons.

Despite her discretion, she has still attracted controversy. She made headlines after being banned from the roads for a year in November 1996, when over the drink-drive limit. In 2000, her car was found crashed into a ditch on the outskirts of Oban, but she denied she had been in the vehicle. A skilled angler, she also had a lucky escape when she fell into a deep water hole while fishing on the River Spey and almost drowned.

In times of turmoil, it has been her religion that has pulled her through. She is a leading figure within the church in Argyll, and raised more than (pounds) 50,000 towards the creation of a Catholic house of prayer on the island of Iona. Mrs Shand Kydd is also patron of such diverse organisations as the Highlands and Islands Music Dance Festival, the Highland Division of the Search and Rescue Dog Association, and Oban Air Training Corps.

She seems to find a purpose in devoting her life to helping others, and spends time comforting the bereaved families of fishermen, often driving for hours to reach their homes. Mrs Shand Kydd has also made some 15 pilgrimages to Lourdes with groups of disabled people. ''I find it a great privilege to be in their presence,'' she says. ''They are an inspiration that helps put life into perspective.''

It is possible she has continued to keep the world at bay to avoid strangers expressing their grief to her. ''Over the years, since my daughter died, I have done more consoling than being consoled,'' she said. ''The number of people who come up to me and mention Diana's name, then burst into tears, is simply unbelievable. They're trying to be kind to me, but, often, it's really difficult to cope with their pain as well as my own.''

Indeed, she described having to leave a shop when a woman broke down in front of her, sobbing that she loved and missed Diana. This left the late princess's mother so upset she had to abandon her bags and walk away into the street. ''I've only cried in public once since Diana died,'' she said. ''I know it doesn't matter, but I always felt if I started I might never stop.''

At one point, she counted 65,000 letters sent to her home from members of the public looking for words of comfort. ''They forget that I was the grieving mother in all this.''

Although the final rift with Diana has caused her much pain, those who know the Spencer family say that bickering between them is nothing unusual. The Spencers' eldest daughter, Lady Sarah McCorquodale, has clashed with her brother, Earl Spencer, on numerous occasions over her handling of the Diana Memorial Fund. Their other sister, Lady Jane Fellowes, and Diana barely spoke to one another during the divorce from Prince Charles. Lady Jane, being married to a member of the Royal Household, was more in the Windsor camp than on her sister's side.

In many of these situations Mrs Shand Kydd has tried to smooth the waters and act as mediator. It must hurt, then, that a family dispute ruined her last few months with her youngest child.

As a teenager in 1954, Frances Ruth Burke Roche was a young bride marrying an older man, Edward John Spencer, Viscount Althorp. Their first son, John, died when he was barely 11 hours old. The marriage ended bitterly in divorce in 1969, after Frances left Althorp to start a new life in Scotland with wallpaper tycoon Peter Shand Kydd, with whom she had been having an affair. Unusually at the time, Johnny won custody of their four children Sarah, Jane, Charles, and Diana. Diana was only eight, and she must have felt her mother's absence sorely.

The couple set up home on Seil and Mrs Shand Kydd opened a gift shop in Oban. Things went wrong once more when her second husband left her for a younger woman. Horrified at being in the glare of publicity, she closed her shop and, apart from her charity work, became a virtual recluse. She prefers not to dwell on her failed marriages but, at Diana's funeral, memories came flooding back when she realised the last time she had walked up that Westminster Abbey aisle was when marrying the princess's father.

''That was something I had to digest and get on with,'' she said. ''It was painful, but probably the proudest day of my life as a mother. I felt so proud of Diana, of my two daughters, who were rock steady in their readings, and my son, who I thought gave the ultimate tribute of brotherly love.''

Appearing in court this week must have been traumatic for a woman who has rarely spoken publicly about the death of her daughter, preferring, instead, to try to find peace in the normality of the island community where she is protected and respected by locals.

Each anniversary of her daughter's death, she goes to the same deserted beach, with no phone calls from newspapers or people at her door. She says it allows her to remember her daughter the way she chooses. With all the intrusions on her family's life since the accident, she has noted: ''Sometimes I think the only one resting in peace is Diana.''

Despite moments of snatched tranquillity and the religion she clings to tightly for comfort, it is clear that nothing will ever totally assuage what she has described as ''the ache that never goes''.