Great Britain 1965 4d-1s Centenary of Joseph Lister Discovery of Antiseptic (Phosphor), SG667/8pvarGreat Britain 1965 4d 1s Centenary of Joseph Lister Discovery of Antiseptic (Phosphor), SG667 8pvar. Superb unmounted mint, with full original gum, top marginal set of two imperforate imprimaturs, each stamp with a "BPMA" handstamp on reverse. A scarce set of of imprimaturs from the first approved printing sheets. Exceptional provenance as they were released from the British Postal Museum Archives in 2014. Prior to this they were stored in the museum