 Led by Vickers-Armstrongs' chief designer Rex Pierson; a key feature of the aircraft is its geodetic airframe fuselage structure, which was principally designed by Barnes Wallis.Development had been started in response to Air Ministry Specification B.9/32, issued in the middle of 1932, for a bomber for the Royal Air Force.This specification called for a twin-engined day bomber capable of delivering higher performance than any previous design.