During the German occupation, Norwegians already abroad, or those escaping from occupied Norway, ensured a constant supply of flight and ground personnel. On the 21st of July 1941 No.331 (Norwegian) Squadron was formed at Catterick in Yorkshire. Operationally it was under the control of the RAF. The RAF unit code was FN, and legend has it that this stands for "First Norwegian". That, however, has never been officially acknowledged.