Princes William and Prince Harry are in mourning following the death of their former nanny.
Olga Powell, who lived with the young royals for 15 years, passed away after suffering a fatal heart attack on her doorstep.
The 82-year-old widow is said to have treated William and Harry like family, helping them through their parents' divorce and the death of their mother Princess Diana.
A Kensington Palace spokesman said: "The princes have been informed and are very saddened to hear the news."
Ahead of the royal wedding last year, Powell, who was guest at the nuptials, revealed that she had remained close to the brothers.
In the interview with the Hertfordshire Mercury she insisted that they "were just like any other children" and "like my grandsons".
"I have a very normal relationship with them," she added. "Their upbringing was very normal and their parents wanted them to have as ordinary a childhood as they could."
As a close family friend, she attended William's passing-out parade at Sandhurst in 2006, Prince Harry's confirmation at Eton in Berkshire in 2000 and also went on various family holidays.