Lot 51140 – 1921-29 Wmk Script 2s purple and blue on blue with “SPECIMEN” DOUBLE OVERPRINT error

1921-29 Wmk Script 2s purple and blue on blue with “SPECIMEN” DOUBLE OVERPRINT error, mint og, very fine, a very rare and remarkable phenomenon, being one of very few recorded double specimen overprints on any De La Rue stamp and although the size of the forme is unknown, it seems most unlikely that an entire sheet existed