Two companies built aircraft to meet Specification C16/28 for a bomber transport and neither received a production order: Gloster produced the four-engined biplane TC33 while Handley Page produced the Type 43 three-engined biplane which bore a very close resemblance to the HP42. Indeed, the sesquiplane wing arrangement appeared to be almost identical except for the removal of the centre section of the top wing and an equivalent length from each anhedral stub of the bottom wing. The drag strut arrangement in the wing bays was also changed. The third Bristol Pegasus was mounted under the top wing at the centre-line while the other two Pegasus simply replaced the Jupiters of the HP42 arrangement. The undercarriage was similar but with drag loads being taken by a strut to the fuselage rather than to the rear spar, as before. An angular, fabric-covered metal tube fuselage replaced the metal-covered one of the HP42 and the monoplane tailplane was fitted with twin fins and rudders. Thirty troops could be carried and defensive armament comprised open nose and tail positions with Scarff-rings for single Lewis guns.
Major Cordes flew the HP43, J9833, on its maiden flight from Radlett aerodrome on 21st July 1932. Although no production order was received, the HP43 led to orders ultimately when its fuselage was married, some three years later, to a new monoplane wing on the HP51 which led directly to the monoplane Harrow.