At the moment, Prince William and Kate Middleton are the Duke and Duchess of Cambridge. But that title will change when he will eventually inherit the crown as he will be given a new lengthy title that is similar to that of his grandmother, the Queen.
Queen Elizabeth II is officially titled “Elizabeth the Second, by the Grace of God, of the United Kingdom of Great Britain and Northern Ireland and of Her other Realms and Territories Queen, Head of the Commonwealth, Defender of the Faith, with the style of ‘Majesty.’” Of course, the title can be quite a mouthful that she is sometimes referred to by the shorter “Her Majesty the Queen.”
Similarly, William will likely be officially titled “William V, by the Grace of God, of the United Kingdom of Great Britain and Northern Ireland and of His other Realms and Territories King, Head of the Commonwealth, Defender of the Faith’, with the style of ‘Majesty.’” Of course, the lengthy title will be shortened, and just like his grandmother, William will likely be referred to as “His Majesty the King.”
But it will likely take some time for Prince William to become king since it will be his father’s, Prince Charles’, turn first. Interestingly, William and Kate’s title will even become more confusing when Prince Charles ascends the throne.
According to royal historian Marlene Koenig, Prince William and Kate will likely inherit Prince Charles’ titles should the latter finally become the monarch. This means that they will earn two more royal titles when Charles becomes king.
Prince Charles was given the title of His Royal Highness the Duke of Cornwall in 1952, a title that he holds up to the present. In 1958, he was given another title as His Royal Highness the Prince of Wales, a title that he also continues to hold until now.
When he becomes king, Charles could choose to gift these two titles to his successor, Prince William. Thus, William and Kate could also be called Duke and Duchess of Cornwall, as well as Prince and Princess of Wales. This is on top of their current title Duke and Duchess of Cambridge, which was given by Queen Elizabeth after their wedding seven years ago.