Great Britain 1870 1½d rose red Plate 3 imprimatur, SG51Great Britain 1870 1d rose red Plate 3 imprimatur, SG51. A superb unused right hand marginal imperforate imprimatur lettered 'BL'. Very rare, one of only 23 possible examples many of which are in institutional collections. Plate 3 was registered on 13 April 1874 and put to press on 10 August 1874. These imprimaturs represent the first sheet printed of a stamp issue from the approved and finished printing plate, the equivalent to the first edition of