Saro Windhover

The Saro A.21 Windhover was a British amphibious aircraft from the period between World War I and World War II, constructed by Saunders-Roe, or "Saro". It was originally advertised as the A.19 Thermopylae after the famous clipper ship, being an enlarged version of the Saro Cutty Sark.
Development.
When tests to improve the power of the Saro A.17 Cutty Sark by adding a third de Havilland Gipsy II engine proved impractical (due to the additional weight on the small airframe), Saro designed a larger aircraft on similar lines that could indeed carry three Gipsy II engines. Although a technically successful aircraft and nearly viceless in service, it was a type with a very limited market and only two were built.