09/30/2011. A contender to Specification O.22/26 calling for a high-speed shipboard reconnaissance-fighter capable of being flown with either wheel or float undercarriage and suitable for catapult operation from cruisers and larger warships, the S.10 Gurnard was awarded a two-prototype contract.
One of the prototypes, the Gurnard Mk.I, was to be powered by a 525 hp Bristol Jupiter X nine-cylinder air-cooled radial engine, and the other, the Gurnard Mk.II, was to have a 525 hp Rolls-Royce Kestrel IIS twelve-cylinder water-cooled V-engine. A single-bay biplane of metal construction with fabric skinning, the Gurnard had an armament of one fixed forward-firing 0.303 in (7.7 mm) machinegun and a similar-caliber weapon on a Scarff ring for the second crew member.
The Gurnard Mk.II was the first to fly, on April 16, 1929, as a floatplane, the Gurnard Mk.I following in landplane form three weeks later, on May 8. Both prototypes were tested at the A&AEE, but the Hawker Osprey was selected in preference and no production of the Gurnard was ordered. The Gurnard Mk.II was flown - commencing on June 15, 1931- as an amphibian with a single main float.