Saunders-Roe London
The Saunders Roe A.27 London was a British military biplane flying boat built by the Saunders Roe company. Only 31 were built, entering service with the Royal Air Force in 1936. Although due for replacement by the outbreak of World War II, they saw some active service pending the introduction of the ultimately unsuccessful Lerwick.
The A.27 London was designed in response to the Air Ministry Specification R.24/31 issued for a "General Purpose Open Sea Patrol Flying Boat" and was based on the Saro A.7 Severn. The London and its contemporary, the Supermarine Stranraer, were the last multi-engine, biplane flying-boats to see service with the RAF. The design utilized an all-metal corrugated hull and fabric-covered wing and tail surfaces, with two Bristol Pegasus II radial engines, mounted on the upper wing to keep them clear of spray while taking off and landing.
The first prototype first flew in March 1934 and then went on to serve until 1936 with 209 and 210 Squadrons RAF at RAF Felixstowe and Gibraltar respectively.
Gradually, the Londons' duties were assumed by newer aircraft such as the Lockheed Hudson, while squadrons flying Atlantic and Mediterranean patrols were re-equipped with Short Sunderlands. Some Londons were transferred to the Royal Canadian Air Force. All were withdrawn from front-line duties by the middle of 1941. Wikipedia