GREAT BRITAIN 1963 (VARIETY) 5S CAERNARVON CASTLE PRINTED ON THE GUMMED SIDE
5s Caernarvon Castle single, from plate 1A printing by Bradbury Wilkinson on white paper with multiple crowns watermark, printed on the gummed side in error. Very scarce. Just 30 examples recorded. Fresh and fine. Mint never hinged. SG596ab; SC372var
