The Prince of Wales is no longer able to attend a thanksgiving service held in honour of his godfather, King Constantine II of Greece, HELLO! understands.
William had been due to give a reading at the memorial which is taking place on Tuesday morning at St George's Chapel, Windsor Castle. Constantine's eldest son Crown Prince Pavlos will do the honours instead.
It's understood William pulled out last-minute due to a "personal matter" and he spoke privately to the Greek royal family in advance to apologise for his absence. His wife Princess Kate continues to be recovering "well" at home.
Queen Camilla attended on behalf of her husband King Charles, who was a close friend and second cousin of Constantine. The pair got on so well together that Charles, 75, asked Constantine to be one of William's godfathers upon the Prince's birth.
Charles sadly had to miss Tuesday's service due to his ongoing treatment for cancer, and also couldn't make Constantine's funeral in Athens last year due to a prior commitment with the President of the Republic of Cyprus. His sister Princess Anne travelled to Greece in his place.
Other royals who attended the thanksgiving service included Prince Andrew, Sarah Ferguson, Princess Anne, Zara Tindall and Princess Beatrice.
Constantine's widow Queen Anne-Marie, former Queen of the Hellenes, and the couple's eldest son Crown Prince Pavlos, led the Greek royal family in attendance.
Constantine and Anne-Marie's four other children also flocked to Windsor: Princess Alexia, Prince Nikolaos, Princess Theodora, and Prince Philippos.
The service took in the nave of St George's Chapel, led by the Dean of Windsor, The Right Reverend Dr Christopher Cocksworth.
Constantine died at the age of 82 in January 2023. He had been suffering from ill health for a number of years and was treated at the private Hygeia Hospital in Athens.
The funeral took place at the Metropolitan Cathedral in Athens, with a whole host of European royals in attendance, including Constantine's older sister, Queen Sofia of Spain, and Anne-Marie's sister, Queen Margrethe II of Denmark.
The guest list was also made up King Willem-Alexander and Queen Maxima of the Netherlands, King Felipe, his sister Infanta Cristina, Queen Mathilde and King Phillipe of Belgium, and Queen Silvia and King Carl XVI of Sweden.