SG828 1/6 Dickens NPM IMPRIMATUR (Only 7 NPM known) U/M Cat 2250 pounds

1970 1s6d Literary Anniversaries (1st series) Grasmere imperforate single (imprimatur) stamped N P/ IMPRIMATUR in black on reverse Pierron reports only 3 singles and a block of 4 NPM examples. There are other examples take later from the sheet handstamped BPMA. Fine unmounted o.g. Cat 2250 pounds