Hawker Henley The Hawker Henley was a British two - seat target tug derived from the Hawker Hurricane that was operated by the RAF during the Second World War . Design and development . In 1934 Air Ministry Specification P . 4 / 34 was issued which called for a light bomber that could also be deployed in a close - support role . Fairey , Gloster and Hawker all rushed to fulfill this need , and competition was tight to attain the highest performance possible . As the aircraft required only a modest bomb load , and with performance being paramount , the Hawker design team chose to focus its efforts on developing an aircraft similar in size to their Hurricane fighter . The Hurricane itself was then in an advanced design stage , and it was thus beneficial both economically and production - wise if some assemblies could be common to both aircraft . This resulted in the Henley , as it was to become known , sharing identical outer wing panel and tailplane jigs with the Hurricane . Both were also equipped with the Rolls - Royce Merlin engine as it offered the best power / weight ratio as well as a minimal frontal area . The Henley ’ s cantilever fabric - covered monoplane wing was mid - set , retractable tailwheel type landing gear was selected , and accommodation provided for a pilot and observer / air gunner , which differed from the Hurricane ’ s single - seat accommodation . Although construction of a Henley prototype began as early as mid - 1935 , with all priorities going to Hurricane development it was not until 10 March 1937 that it was first flown at Brooklands , powered by a Merlin " F " engine ; shortly after the competing Fairey P . 4 / 34 . Subsequently the aircraft was refitted with light alloy stressed - skin wings and a Merlin I engine , and further test flights confirmed the excellence of its overall performance . It could reach a top speed of . However , the Air Ministry had by this point decided that it no longer required a light bomber , and the Henley was thus re - designated as a target tug . Henley production was subcontracted to Gloster Aircraft , and 200 were ordered into production . The second prototype was fitted with a propeller - driven winch to haul in the drogue cable after air - to - air firing sorties , in recognition of its new role , and was first flown on 26 May 1938 . Operational history . Production aircraft , designated Henley III , entered service with Nos . 1 , 5 and 10 Bombing and Gunnery Schools , as well as with the Air Gunnery Schools at Barrow , Millom and Squires Gate . Unfortunately , it was soon discovered that unless the aircraft were restricted to an unrealistically low tow speed of 220 mph ( 355 km / h ) , the rate of engine failures was unacceptably high . This resulted in Henleys being withdrawn from this role and relegated to towing larger drogue targets with anti - aircraft co - operation units . Predictably , the Henley proved to be even more unsuited to this role , and the number of engine failures increased . Several Henleys were lost after the engine cut out and the drogue could not be released quickly enough . A solution was never found to this problem , and in mid - 1942 the Henley was withdrawn from service , and replaced by Boulton Paul Defiant s , as well as purpose - built Miles Martinet s .