Great Britain 1974 5½p "Birth Centenary of Sir Winston Churchill", SG963varGreat Britain Queen Elizabeth II 1974 5p "Birth Centenary of Sir Winston Churchill", SG963var. A superb unmounted full original gum bottom left hand corner marginal "Traffic light" block of four imperforate imprimaturs each with a "BPMA" (British Postal Museum Archives) handstamp on reverse. Imprimaturs represent the first stamps printed from the approved and finished printing plate. Exceptional provenance originating from the British Postal Museum