The aircraft was of mixed construction having fabric-covered, two-bay metal-frame wings,[REF] while the fuselage had an aluminium monocoque forward section with a fabric-covered frame to the rear,[REF] It had a crew of four, consisting of a pilot, a bomb aimer/navigator/gunner, a radio operator and a dorsal/ventral gunner.
The HP.38 proved successful during service trials at Martlesham Heath and with No. 10 Squadron RAF and was chosen as the winner of the B19/27 competition, being ordered as the HP.50 Heyford.