Great Britain 1918 3d violet "Postage due" (Harrison printing) imprimatur, SGD5varGreat Britain 1918 3d violet "Postage due" (Harrison printing), SGD5var. A very fine unmounted mint bottom marginal pair of imperforate imprimaturs with full original gum, each stamp with a "BPMA"handstamp on reverse. Some light gum wrinkling as was prevalent across the whole sheet. A scarce imperforate pair of imprimaturs from the first approved printing sheet. Exceptional provenance as they were released from the British Postal Museum Archives in