South Africa 1913 KGV 1d Missing Watermark, Rare

1913 KGV 1d rose-red variety MISSING WATERMARK (SG 4wvar). VF/UM (light hinge in margin) vertical pair with interpanneau margin, top stamp MISSING WATERMARK and bottom stamp INVERTED WATERMARK. The missing watermark is listed as UHB variety V15 (from plates 6 & 7) with only 48 examples possible. Lovely representation illustrating the affected sheet position of the error. Rare.