SOUTH AFRICA SGO20 Official 1935 1/2d grey and green WMK INVERTED block of 6 U/M

Official. 1935-49 1/2d grey and green WMK INVERTED lower left corner block of 6 (2×3) fresh unmounted o.g. (hinged in margins). Very scarce positional multiple. Purchased from Stanley Gibbons (still on their card)