His brother Prince Michael of Kent is styled as a prince, while the Duke of Kent is styled as a duke.
The Royal Family’s website explains this title decision as a royal custom.
The website reads: “In the British Royal Family a son of a monarch is a royal prince and he is given the title of duke on his marriage.
“Prince Michael’s father, Prince George, was made Duke of Kent when he married Princess Marina of Greece, Prince Michael’s mother.
“The title Duke of Kent was inherited by Prince Michael’s older brother.
“If his parents had more sons they would also have had the title of Prince, only the eldest inheriting the ducal title.”