85a (147) 1878 (1¢) on 4¢ blue Seal of the Colony overprinted OFFICIAL surcharged with one horizontal bar and one vertical bar, only one sheet was surcharged for postal use, extremely rare, and considerably undercatalogued, one of the great basic perforated Ship rarities in all of British Guiana and considerably undercatalogued, well centered, lightly canceled.
