Peter Phillips will automatically relinquish his birthright to the throne when he marries his Catholic fiancée.
The 30-year-old royal, the son of Princess Anne, will officially lose his place as 11th-in-line to the throne when he weds Autumn Kelly at the queen’s Berkshire residence Windsor Castle on May 17.
The 1701’s Act of Settlement prevents any Roman Catholic from ascending the throne. The act states anyone who marries a “Papist” will be “forever incapable to inherit, possess or enjoy the Crown”.
Autumn, a 29-year-old Canadian management consultant, was baptised in a Catholic church in Montreal in 1978, and her mother Kitty insists her daughter is “proud of her religion”.
The couple – who met at the Canadian Grand Prix in 2003 – already live together in a cottage on Princess Anne’s Gloucestershire estate Gatcombe Park.
Peter will not be the first royal to renounce his claim to the throne.
Prince Michael of Kent married Marie-Christine von Reibnitz in 1978, and automatically gave up his claim to the throne because his new wife was a divorced Catholic.