The Bristol Blenheim was a WWII British light bomber used mainly during the first two years of WWII. Initially developed as a civilian airliner, it was modified and delivered to RAF squadrons in 1937. The Mk IV was used as a long ranger fighter and marine patrol aircraft as well as a light bomber and gunnery trainer. The Mk IV was powered by two 905hp Bristol Mercury XV radial piston engines and could carry a 1,000lb bomb load internally and a further 320lb load externally.