Great Britain 1902 £1 Dull blue green (I.R. Official). SG O27Great Britain 1902 1 Dull blue green (I. R. Official), SG O27. Superb unused original gum example of this very rare departmental issue printed by De La Rue. These Official stamps were for the sole use of essentially autonomous Government Departments. None of these Departmental overprints were supposed to be sold, or otherwise made available to the public in unused condition. Accompanied by a 1942 Royal Philatelic Society & 1995 British Philatelic