[OP] 1841 1d.: Plate 77:
"B blank" error with the "A" omitted, an example on small piece tied by Scottish numeral cancel, just cut into at top left otherwise good margins, R.P.S. Certificate (1961) (when the piece was slightly larger) states "...genuine, slightly defective at N.W.", with two publications where it was illustrated and photocopies of three of the other known examples, a fine and rare item. SG Spec. BS29a, £10,000.