Blue on Blue
Blue on blue was most usual! 602 Sqn spitfires from Drem shot down two of 44 Sqn's Hampdens in December 1939 despite recognition flares being fired - sadly, one crew member lost his life. And, at the risk of thread drift - Adrian Warburton ordered his gunner to shoot down a Malta based Hurricane that persisted in attacking his Glen Martin on return from a mission. The gunner duly obliged although I do not remember whether this "kill" is one of the 9 accredited to Warburton. Interestingly, both Bader and Gibson (from the same school as Warburton) were also probable victims of Blue on Blue.