The Supermarine Stranraer marked the end of biplane flying-boat devlopment for the Royal Air Force. Built to Air Ministry specification R.24/31, they entered service from April, 1937. Many were still in service at the outbreak of the Second World War and flew anti-submarine and convoy escort patrols. They were withdrawn from operational service in March 1941, but continued to serve in a training capacity until October 1942.
The structure was mainly duralumin, with the hull covered with sheet metal and the wings with fabric. 17 Stranraers were built in Britain and 40 in Canada, serving with the RCAF until 1945. Some units passed into civilian use after the war; notably several Stranraers saw service with the Queen Charlotte Airlines in British Columbia, Canada.