http://forum.keypublishing.co.uk/showthread.php?t=66366
http://forum.keypublishing.co.uk/showthread.php?t=66851

A couple of threads by the resident Spitfire experts on the details of different Spitfire armaments, different cannon fairings etc. Restored aircraft are not a good guide – the individual components may be correct, but combinations of armament ports are present on restored Spitfires that never existed on wartime aircraft.