Great Britain 1872 4d vermilion Plate 12 overprinted "SPECIMEN" type 6, SG94var.

An exceptionally fine and fresh unmounted mint, with full original gum, interpane marginal block of twenty, lettered 'AE–EH', overprinted in horizontal pairs.

The top pair 'AE–AF' is particularly striking, the AF stamp showing the entire overprint due to a rare double application being an unusual and previously unrecorded printing variety.

GB Specialised Catalogue No: J59t.

Last sold by Stanley Gibbons in 2009 for £12,000.