Great Britain 1964 2½d 20th International Geographical Congress (Ordinary) imprimaturs, SG651var.
A superb unmounted mint, with full original gum, imperforate left hand marginal horizontal pair of imprimaturs with "BPMA" handstamps on reverse, showing variety "Retouched lawn" in position R11/1.
A unique extract from the first approved printing sheet.
Exceptional provenance as it was released from the British Postal Museum Archives in 2014. Prior to this it was stored in the museum archives in climate controlled vaults since being printed and is therefore in uncirculated mint condition.
GB Specialised Catalogue No: W46c.
Previously sold by Stanley Gibbons in 2015 for £5,000.
