90c Purple, Plate Proof on Card (218P4).
Bottom imprint and plate no. 23 strip of seven, large margins, rich color, Very Fine and choice, a most unusual item, Scott 218 was printed by American Bank Note Co. yet this has a National Bank Note Co. imprint, it is likely this was struck by ABN Co. as they inherited the plates, Scott Retail as singles with no premium for the imprint and plate no.
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