Cover with typed 'Red Cross Postal Message Scheme' at top franked with single 1938 2/- deep purple & ultramarine on grey blue GVI 'Key Type' issue line perf 14½ (SG 116b) tied by HAMILTON cds dated 30 MAR 1942 with nice multicoloured 'TRANS ATLANTIC AIR MAIL VIA PAN AMERICAN CLIPPER' airmail label. Addressed to the 'Comite International de la Croix Rouge' SWITZERLAND with LISBON, PORTUGAL transit mark on reverse. An exceptionally rare stamp genuinely used on cover.