on 3d. green [42], unused with part original gum; tiny gum thin in centre otherwise fine. Rare. B.P.A. Certificate (1998). S.G. 20, £1600. Photo" /> unused <I>"Six/Cents"</I> on 3d. green [42], unused with part original gum; tiny gum thin in centre otherwise fine. Rare. B.P.A. Certificate (1998). S.G. 20, £1600. Photo | Christie's