During the 1920s, Britain's air defences had been based around interceptor aircraft capable of flying only for short ranges and at speeds of 150-200 MPH; however, by 1930, figures within the Air Ministry were keen to supersede these aircraft. In particular, there had been some dissatisfaction with the level of reliability experienced with the 'one pilot, two machine guns' design formula previously used, the guns often prone to jams and being unreliable.[3] The Air Ministry's technical planning committee formulated Specification F.7/30, which sought a new aircraft capable of a maximum speed of at least 250 mph (400 km/h), an armament of no less than four machine guns, and such handling that that same fighter could be used by both day and night squadrons.[3] Gloster, being already engaged with development of the Gloster Gauntlet, did not initially respond to the specification, which would later prove to be beneficial.[4]