South Africa 1947 ½d PO Museum "Proof" Imperf Frames Only

1947-54 ½d grey & green IMPERF BLOCK OF FOUR, FRAMES ONLY (SG 114var). Top marginal ARROW BLOCK superb UM. Very rare, only 24 pairs exist outside the PO/Cultural museum. Exceptionally attractive as positional multiple thus. (KGVI)