Mint N.H. in block with seven normal stamps, top right pair the error, showing radical misperforation creating the Scott-listed error, diagonal crease affects the error pair (which is what caused this dramatic error)
This perforation error was caused when the sheet was accidentally folded at the corner before going through the perforating machine. This caused the double perforations along the top two stamps at right. This block and another similar block were both offered in the 2001 William Floyd sale. The second block was rejected by the Scott Catalogue editors, because the pair shows the missing perfs within the error pair.
Ex Floyd. With 1987 and 2001 P.F. certificates