Their cruise ships have hosted countless honeymoons for British newlyweds.
Now Cunard is moving into the wedding business itself by allowing couples to marry at sea on board its liners at an estimated £1500 (NZ$3107) a time.
But a quirk in marriage laws means the move will break a link with 170 years of maritime history, as the registered home of the luxury liners has had to be shifted from Southampton to Bermuda.
Carnival, the American company which owns Cunard and a number of other cruise firms, carried out 2200 marriages on its ships last year.
However, British law does not allow ocean-going ships to be used for weddings because they are not accessible for members of the public who want to object during the ceremony.