[1] The H.S.T.10 was a low-wing cantilever monoplane powered by two Napier Rapier VI engines.

It had a retractable conventional landing gear with an enclosed cabin for two pilots and twelve passengers.

The single tubular spar, known as the Blackburn-Duncanson, had previously been tested on a Blackburn Segrave.

Intended to be "high speed" by careful attention to shape and removing "protuberances" with retractable undercarriage, the expected performance was 320 miles with two pilots and twelve passengers which increased to 1000 miles with both pilots and five passengers.

Configurations drawn up by Blackburn included 12- and 8-seat passenger cabins or 4 bunks/stretchers as a medical transport.