The Duke has described how hearing the news of his friend’s death took him back to the moment in 1997 when his father, then Prince Charles, told him that his mother had died.
He noted in his memoir that, “just like Mummy”, Henry was not wearing a seatbelt.
“The news must have come in the form of a phone call, though I only dimly recall holding the phone, hearing the words,” he wrote.
Both Harry and William attended the funeral, with the Duke recalling how he had queued up to hug Henry’s parents, Alex and Claire, and his two brothers.
The Van Straubenzees have often been described as being like a second family to the Prince and the Duke.
Thomas, now 41, and Charlie, 35, remain close to the Princes.
Both were ushers at the Duke’s wedding to the Duchess of Sussex in 2018 and Charlie gave a speech at the reception.
The Duke is godfather to Charlie’s daughter, Clover, four and Charlie is a godfather to Prince Archie, who turned five on Monday.
In May 2022, Charlie was photographed out cycling with the Duke near his home in Montecito.
Thomas, who is godfather to Princess Charlotte, is often described as the Prince of Wales’s best friend.
Both William and Harry were ushers at his first wedding in June 2013 to Lady Melissa Percy at Alnwick Castle, the Percys’ ancestral home which also serves as the setting for Hogwarts in the Harry Potter films.
The couple have since divorced and in July 2020 Mr Van Straubenzee, a property consultant, married Lucy Lanigan-O’Keeffe, a teacher at Thomas’s Battersea, in south-west London, where Prince George and Princess Charlotte were once pupils.
William is godfather to their young daughter, Mary.