The Boulton Paul Defiant NF.1 was a British Nightfighter and Bomber Interceptor in service with RAF early in WWII. The Defiant was a two seat single engine aircraft armed with a dorsal turret mounting four 0.303 inch Browning guns. The idea was that an aircraft with a turret mount would be able to take on bombers from below or from the side without being exposed to the bombers own guns. In practice, without forward firing guns, the Defiant was vulnerable to the more maneuverable ME 109.