The young couple is currently expecting a baby and authorities in Britain are fast-tracking a new law to change the rules on succession so if the child is a girl, she will be allowed to rule after her father - a right traditionally reserved for male heirs.
The Queen has now issued a formal decree to declare all of the couple's children will be given royal titles, instead of just the first boy. The ruling means that if Catherine gives birth to a baby girl, she will receive the title of Princess.
All boys after their first-born son will also receive the title of Prince.
The decree was issued on 31 December (12), but was not made public until Wednesday (09Jan13).