Seafaring and the rule of the waves — as the song would have it — was an integral part of Britain’s sense of identity for centuries, a fire in the national imagination arguably first sparked by the exploits of Sir Francis Drake and the defeat of the Spanish Armada, rising to full flame with the Battle of Trafalgar and the expansion and consolidation of the Empire, and finally dwindling to embers as imperial ambitions failed and ownership of the seas passed to the United States.