Harry Beck original vintage underground railway map 1956

Harry Beck original vintage underground railway map 1956. London Underground ‘Diagram of Lines and Station index. Original 1956 map by H.C. “Harry” Beck, dated 1956 in bottom right of front cover (see scan in Product Gallery.) Shows H.C. Beck imprint at bottom left corner of diagram. Published the year of the Soviet crushing of the Hungarian Revolution. Printed by Johnson Riddle & Co. Ltd, St. Mary Cray, Kent. Size approx. 9 x 6 inches. Excellent condition.