RAF / Air Ministry recognition cards, Blue pack, July 1941. Marked 'For Official Use Only'. A 'key' sheet shows various silhouettes of allied and enemy aircraft to be memorised. The pack of cards was then used to test recognition of these aircraft. Normally issued in boxes of four individual packs - each pack colour coded (Red, Blue, Green and Orange). Several different sets were produced during the war, this pack dating from 1941. This pack features mainly bomber aircraft and includes the Ju.88, He.III, Blenheim IV, Wellington I and Stirling I. Full set of 52 cards plus 'joker'. The key sheet is folded/creased. The cards are in excellent condition but the box shows age related soiling. Stock code P19783.