141877 1850 1D PL.98 ARCHER EXPERIMENTAL PERFORATION (SG16b) EXCEPTIONAL UNMOUNTED MINT BLOCK OF FOUR.

 1850 1D PL.98 ARCHER EXPERIMENTAL PERFORATION (SG16b) EXCEPTIONAL UNMOUNTED  MINT BLOCK OF FOUR. An exceptional unmounted o.g. block of four 1850 1d pl.98 ARCHER EXPERIMENTAL PERFORATION (SG16b) lettered OA OB PA PB with superb colour. Block shows unusual but consistent perforations at lower right of both right hand stamps. A quite superb block of exhibition quality. (Ref 141877).