Unique 1882-94 QV 3d "O S" with Tilted Orange-Red Overprint

Extremely rare 1882-94 QV 3d "O S" in orange-red overprint on yellow-green paper. Perforation 2 x 11with a large crown/NSW inverted watermark. "O S" overprint tilted inclining upwards. In MUH condition and the only known example of this variety in any condition.