The first prototype, with the B-class serial "U-9" first flew on 15 September 1940, and was tested at the A & AEE under the military serial number "AX834" against Specification F.19/40. Armed with eight .303 Browning machine guns like the Hurricane, the M.20 prototype was faster than the Hurricane but slower than Spitfire types then in production, but carried more ammunition and had greater range than either. As the Luftwaffe had been defeated over Britain, the need for the M.20 had vanished and the design was abandoned without entering production. The first prototype was scrapped at Woodley.