OAS letter from FPO 306 on 28 April 1940 to Keighley, Great Britain. Stamped 'FIELD POST OFFICE 306 - 28 AP 40' Reykjavik and boxed censor mark 'PASSED BY CENSOR No. 2351' and signature. Registration fee 3d paid with adhesive, registration label 'R / 28' and stamped with the same FPO mark. Rare