1925 International Geographical Congress complete set of three (from the first printing) with SPECIMEN overprints, no gum, minor wrinkles, extremely rare as only 3 such sets exist

Note: The London Post Office Records received commemorative stamps from the UPU as they were issued and were handstamped SPECIMEN on arrival and placed on album pages as the Official GPO reference. In October 1979 they were sold through Robson Lowe’s auction in Basle