Official. 1949 UPU set of 4 to 2½a, in complete IMPERFORATE sheets of 50 (5x10), each with imprint and '1B 1B' (1a) or '1A 1A' plate numbers, very fine unmounted o.g. Now very scarce in this form. (cat £1100+). [N.B. These imperforate stamps are now known used on commercial cover].