10/31/2010. Remarks by Johan Visschedijk: "Specification B.3/34 was promulgated to bring forth an experimental twin-engine, heavy night bomber landplane, and the tender for Handley Page was a derivation by Dr. Gustav V. Lachmann of his earlier H.P.51. Designated H.P.54, the new machine was of approximately the same size but of far less angular aspect. Stringers from nose to tail faired the fuselage to a pleasant oval section, and a pair of 830 hp BristolPegasus X nine-cylinder air-cooled radial engines replaced the H.P.51's Armstrong Siddeley Tigers. Glazed gun positions were provided in the nose, dorsal and tail positions.
The prototype and first production H.P.54, s/n K6933, made its maiden flight from Radlett on October 10, 1936, piloted by Maj. J.L.B.H. Cordes, but the Air Ministry had already ordered 100 in August, 1935, to Specification B.29/35 as an interim heavy bomber. Eighteen more examples appeared as Harrow Mk.Is with the Pegasus X, s/n K6935 to K6952, but were superseded on the production lines by the Mk.II fitted with a pair of 925 hp Pegasus XXs, s/n K6934, K6953 to K7032. Six Mk.Is, s/n K6933, K6935 to K6939, were retrospectively modified to Mk.II by installing Pegasus XXs.
The Harrow carried a crew of five and an internal bomb load of 3,000 lb. Its armament consisted of four Lewis guns disposed one each in the nose and amidships and two in the tail, all three turrets being power-operated. No. 214 Squadron became the initial unit to receive the graceful Harrow, its first Mk.I arriving on January 13, 1937, the last Mk.II was delivered in December 1937. The Harrows served as a bomber until late 1939, many being converted to transports and crew trainers from March 1940 on.
In 1938 K6933 was overhauled by Handley Page at Radlett and converted into a tanker for Flight Refuelling Ltd. at Ford, Sussex, together with K7027 and K7029. All three were transferred to the civil register, K6933 and K7029 respectively as G-AFRG and G-AFRH on February 15, 1939, and K7027 as G-AFRL on March 6, 1939."