South Africa SGO18a 2/6 spectacular DOWNWARD MISPLACED OPT (bottom pair U/M)

Official. 1930-47 Set 9 (= 1934 issue) 2/6 green and red-brown roto SUIDAFRIKA one word SG type O2 opt (21mm space) lower right corner block of four (R19-20/5-6) showing spectacular DOWNWARD MISPLACED OPT (by at least one row) with all four words then falling also in the margin fresh o.g. (lower pair unmounted). Characteristic blue crayon strokes in right margin indicate that the error was noticed and intended to be discarded. A wonderful exhibition piece of the highest rarity with only two other horizontal pairs possible and unique in this positional form. Ex Matheson and illustrated on Hisey and Matheson p.84. (Union Handbook O42 var)