Princess Anne's emotional gesture towards Queen Elizabeth II during recent appearance

Prince William also had to miss the event due to a “personal matter”, according to Kensington Palace.

Instead, Queen Camilla led the royals who were joined by the late king’s widow Queen Anne-Marie, their eldest son, Crown Prince Pavlos and other members of the Greek royal family.

Constantine II was a first cousin once removed and sailing partner of the late Duke of Edinburgh and died at the age of 82 in January last year in an Athens hospital.

Charles had a close friendship with Constantine, choosing him as a godfather for his son Prince Wiliam.