Any day now, Prince George and Princess Charlotte will have a new sibling—and like them, he or she will have an impressively long, fancy title. Understanding royal titles can be difficult because members of the family can (and often do) hold more than one, especially after they are married.
Since the gender of Kate Middleton and Prince William’s baby has yet to be revealed, there are two title options. If it’s a boy, his formal title would be, His Royal Highness Prince (Name) of the United Kingdom of Great Britain and Northern Ireland.
If it’s a girl, her formal title would be, Her Royal Highness Princess (Name) of the United Kingdom of Great Britain and Northern Ireland.
While this would be the new baby’s official title, it wouldn’t be the one he or she went by. Royal historian Marlene Koenig told Town & Country that royal children’s titles are styled differently if they are a royal offspring of a duke. This means that since Kate and William are the Duke and Duchess of Cambridge, the royal baby be His or Her Highness (Name) of Cambridge.
But it only gets more confusing from there. Koeing said the new royal will technically be born a commoner. “It sounds complicated, but in the U.K, the only people who are not commoners are the Sovereign and peers of the realm, [people with titles like] Duke, Marquess, Earl, Viscount, and Baron,” she said.
This means Prince Harry is technically a commoner too, and will be until he marries Meghan Markle in May. The Queen has the option to grant Harry and Meghan new titles after marriage.
The new royal baby will be fifth in line for the throne, right behind his sister Princess Charlotte, brother Prince George, father Prince William, and Grandfather Prince Charles.
From: Marie Claire US