Royal children have always been referred to this way at school, including Princes William and Harry, who took on King Charles’ then-title Wales as their surname at school.
Members of the Royal Family traditionally don’t use a surname, as they are simply known by their first name in the public eye and His or Her Royal Highness.
They can also be known by the name of their house, such as Windsor, which may be different to their surname, such as Mountbatten-Windsor.
A declaration made by the late Queen in the Privy Council in 1960, said that male-line descendants of the monarch, without royal styles and titles, shall bear the name Mountbatten-Windsor.