Great Britain 1909 ½d yellow green, SG218b varOne of the great rarities of GB philately with only 13 known examples, this being the only known surviving multiple and therefore unique. Great Britain 1909 d yellow green, SG218b var. A superb unused, with original gum, bottom marginal block of four from positions R. 20 3 4 showing variety doubly printed from control H9. Most importantly, the printing varieties are unmounted mint. One of the great rarities of GB philately with only 13 known examples,