Great Britain 1902 10s ultramarine (I.R. Official), SGO26Finest quality example of one of the key rarities of GB philately Great Britain 1902 10s ultramarine (I. R. Official), SGO26. A superb unused, with original gum, lightly mounted example of this rare departmental issue showing the merest trace of a previous stamp hinge. A magnificent example of one of the key rarities of GB philately. Less than six mint examples are known in private hands and this is certainly the finest example of the two we have