South Africa 1910 2½d Union Commemorative on PO Publicity Card

1910 KGV Union Commemorative 2½d blue (SG 1) on Post Office PUBLICITY CARD "Commemoration Postage Stamp / NOW ON SALE". The stamp handstamped large bold straightline SPECIMEN in violet. Usual two punch holes at top. A remarkably fresh, superior representation free of the usual folds and broken corners as per most of the few surviving. A rare piece.