The Hawker Horsley was a British single-engined biplane bomber of the 1920s. It was the last all-wooden aircraft built by Hawker Aircraft, and served as a medium day bomber and torpedo bomber with Britain's Royal Air Force between 1926 and 1935, as well as the navies of Greece and Denmark. Design and development The Horsley (named after Sir Thomas Sopwith's home of Horsley Towers) was originally designed to meet Air Ministry Specification 26/23 for a day bomber powered by a single Rolls-Royce Condor engine. While the specification called for any production aircraft to be of metal construction, Hawker proposed to build the prototype of wooden construction, gradually switching to a metal structure during production. This was acceptable to the Air Ministry, and an order for a single prototype was placed. The first prototype was flown in March 1925, powered by a engine, and was delivered to the Aeroplane and Armament Experimental Establishment at Martlesham Heath on 4 May 1925. Meanwhile, the Air Ministry revised its requirements, producing Specification 23/25 which increased the required payload from one to two bombs. At the same time, it also issued Specification 24/25 for a torpedo bomber, required to carry a torpedo. The Horsley's ability to cope with the increased loads required to meet these new specifications led to the design being favoured by the RAF, with an initial order of forty aircraft, consisting of ten wooden Mk Is and 30 Mk IIs of mixed metal and wood construction, being placed. Description The Horsley was a large single-engined two-bay biplane. It had a crew of two, comprising a pilot and a gunner/bomb-aimer/radio operator, who had a .303 in (7.7 mm) Lewis gun mounted in a Scarff ring in the rear cockpit and a prone position for bomb aiming. The rear cockpit was also fitted with dual controls. The payload included two bombs, one bomb or a torpedo weighing . The structure was originally all wood, but before production was complete an all-metal structure was introduced, made in what became the famous Hawker system of metal construction. The three methods of construction were designated: Horsley Mk I for the all-wooden aircraft, Horsley Mk II for the mixed material, and (unofficially) Horsley III for the all-metal aircraft. Some aircraft were fitted with floats. Two aircraft, known as the Hawker Dantorp and powered by Leopard II engines were sold to the Danish Government. They had a slightly different