John Harrison, who is Kate Middleton's first cousin twice removed, said he was "over the moon" that he is now related to the future King of England.
He and his wife Val still live in Hetton-le-Hole, County Durham, where the Duchess of Cambridge's great-grandparents once lived.
The latest addition to the royal family has been named Prince George Alexander Louis, but where did the Prince get his names?
The Duke and Duchess of Cambridge have named their son George Alexander Louis, Kensington Palace said.
With the imminent arrival of the Duke and Duchess of Cambridge's firstborn here are some of the more unusual facts about royal babies.