London ? Frances Shand Kydd, who had an often turbulent relationship with her late daughter, Princess Diana, died Thursday at her home in Scotland. She was 68.

Shand Kydd’s health had been failing in recent months and the grandmother of Princes William and Harry had been taken from her home on Seil Island, where she led a reclusive life, to a hospital in nearby Oban a number of times.

A spokesman for her son, Earl Spencer, said Shand Kydd “passed away peacefully this morning, after suffering from a long illness, and this is now a private time for the family to grieve.”

Queen Elizabeth II sent a private message of condolence to Earl Spencer, Buckingham Palace said.

Shand Kydd was born Frances Ruth Burke Roche, daughter of the Fourth Baron Fermoy. Her mother, Lady Ruth Fermoy, was a lady in waiting to the late Queen Mother, and was later said to have promoted Diana’s marriage to Charles.

Prince Charles said his former mother-in-law “will be sorely missed.” Prince William said he had his brother Harry “are very upset by the death of our grandmother and we will miss her a lot.”

Shand Kydd married Edward John Spencer, 12 years her senior, in 1954 at Westminster Abbey. They had three daughters — Diana was the youngest — and one son.

The marriage foundered in 1967 when she fell in love with Peter Shand Kydd, a married wallpaper heir, and the couple divorced in 1969. Shand Kydd remarried in 1969 when the future princess was 8 years old.

Diana stayed with her father after the split and decades later told Andrew Morton, author of the 1992 book, “Diana, Her True Story” that her childhood was very unhappy and unstable.

“The biggest disruption was when Mummy decided to leg it. That’s the vivid memory we have — the four of us (including her brother and two sisters). … People took sides. Various people didn’t speak to each other. For my brother and I it was a very wish-washy and painful experience,” Diana was quoted as saying.

Diana, Princess of Wales, right, chats to her mother, Frances Shand Kydd, in this July 4, 1993, file photo. Shand Kydd died Thursday at her home near Oban in Scotland. She was 68.

Shand Kydd acknowledged she sometimes had a turbulent relationship with her famous daughter.

Testifying two years ago at the theft trial of Diana’s former butler, Paul Burrell, Shand Kydd said she had not spoken to Diana in the last four months of her life and that the princess had returned her letters unopened.

Shand Kydd agreed with a statement by Burrell’s lawyer, Lord Carlile, that Diana, “like many of us, could sometimes be a little tempestuous.”

Diana and her companion, Dodi Fayed, were killed on Aug. 31, 1997, in a crash in a Paris tunnel as their Mercedes was pursued by paparazzi.

In addition to her son, Shand Kydd is survived by daughters Lady Jane Fellowes and Lady Sarah McQuorquodale.