High Quality Content by WIKIPEDIA articles! No. 331 Squadron RAF was a Second World War squadron of the Royal Air Force. It was formed as a fighter squadron at RAF Catterick in Yorkshire on 21 July 1941. The squadron personnel were Norwegian with the exception of some of the ground crew and the Commanding Officer. At first it was equipped with fairly war worn Hawker Hurricane Mk 1s which had to be rebuilt after being inherited from the Polish squadron, becoming operational on 15 September. It provided defence for Northern Scotland, moving to Castletown on 21 August and later to RAF Skeabrae. In May 1942 it moved south to RAF North Weald, having re-equipped with Spitfires in November 1941.