The first prototype of the Short Singapore, also known as the Short S.5 (military designation Singapore I), was a metal hull version of the wooden-hulled Short Cromarty. The biplane design included a single fin and rudder, and was originally powered by two Rolls-Royce Condor IIIA 650 horsepower (480 kW) engines. Its maiden flight was made from Rochester on 17 August 1926, piloted by Shorts' Chief Test Pilot John Lankester Parker. The type did not enter production, but was used by Sir Alan Cobham for a survey flight around Africa. Registered G-EBUP, it left Rochester on 17 November 1927 and arrived at the Cape on 30 March 1928, returning to Rochester on the 4 June 1928. It was displayed at Olympia in July 1929.
The Singapore II (manufacturer's designation Short S.12) which followed was a development of the Singapore I with 4 engines, mounted in tractor/pusher pairs (better known as the push-pull configuration). The single example of this aircraft to be built was first flown on 27 March 1930, also by John Lankester Parker.
From the Singapore II came a design with four engines and triple fins. In 1933 the British Air Ministry ordered four flying boats based upon the Singapore II for trials with squadrons under specification R.3/33. These would be followed by a further production order to specification R.14/34. These aircraft, the Singapore III (manufacturer's designation Short S.19), had all-metal hulls and fabric-covered metal flying surfaces. They were powered by four 675 hp (503 kW) Rolls-Royce Kestrel IX mounted between the wings in two tandem push-pull pairs, similar to the Singapore IIs. The crew of six was located in a central cabin and fore, aft, and midships open gun positions (Vickers machine gun or Lewis gun). A long-range fuel tank could be carried externally on the dorsal hull. The first Singapore III flew on 15 June 1934. Although obsolescent by the time the first aircraft entered service with 210 Squadron in January 1935, the type arrived just in time to benefit from the arms race of the late 1930s and 37 were built. Production terminated in June 1937.