Prince William and Prince Harry's uncle, Robert Fellowes, has died aged 82.
According to The Times, Princess Diana's brother-in-law died of undisclosed causes on July 29.
In addition to being the devoted husband to Princess Diana's sister, Lady Jane Fellowes, Robert was the late Queen Elizabeth's chief adviser for nine years. He guided her through some of her most turbulent years, including the infamous "annus horribilis" in 1992.
Lord Fellowes was also part of a small group of senior courtiers who helped convince the Queen to return to London from Balmoral following Diana's death.
During that time, Robert penned the first draft of the Queen's historic speech when she addressed the crowds as "your Queen, and as a grandmother" to the British public on the eve of Diana's funeral. The final version of this famous speech was written by Lord Fellowes, the Queen, and her private secretary, Sir Robin Janvrin, according to the Times.
In 1978, he married Princess Diana's elder sister, Lady Jane Spencer, and the future royal was a bridesmaid at the wedding.
Following their nuptials, the couple went on to have three children: Laura Fellowes, 44; Alexander Robert Fellowes, 41; and Eleanor Ruth Fellowes, 38. Their eldest daughter, Laura, is one of Princess Charlotte's godmothers.
Despite having a strained relationship with Diana, when she died, he said: "I was deeply fond of her. She was a very good person. She found it difficult in life to find happiness, and I'm sad for people who have that situation."
His marriage to the late Princess of Wales's sister was not his only connection to royal life. His father, Sir William 'Billy' Fellowes, was the land agent at Sandringham from 1936 to 1964, as well as being a shooting companion of the Queen’s father, King George VI.
Meanwhile, his mother, Jane, was the daughter of Brigadier General Algernon Ferguson, a relative of Sarah Ferguson, who went on to become Duchess of York.
In July 1999, Robert was created a life peer in the Queen's Birthday Honours List, giving him the title of Baron Fellowes of Shotesham in the County of Norfolk.