1863 4D RED PL. 3 (SG80) WITH CONSTANT VARIETY 'DEFECTIVE LETTER K', STAMP CK ON COVER (SPEC J52d). Wrapper London to Amsterdam with 1d rose-red on white paper (SG40) lettered KF, also pair of 4d pale red pl.3 (SG80) lettered CK CL, stamp CK clearly showing constant variety 'DEFECTIVE LETTER K' in lower right corner square. Stamps tied London '12' numeral cancellations, on reverse LONDON date stamp FE 25 63 and AMSTERDAM receiver 27 2 63. Rare usage on cover. (Ref 115266).