Los-Nr. 6254

1887, Insufficiently prepaid double rate letter dated Saint Louis (USA) September 10th and sent to Rödeby. Prepaid with 3x 2 cents = 6 cents. The single UPU rate was 5 cents, double 10 cents, thus the missing postage was 4 cents=20 centimes as cancelled on letter. The postage due was 40 centimes. Instead of using the actual UPU rate (1 centime=0,8 öre) the Swedish exchange post offices continued to use the old GPU conversion tables (1 centime=0,72 öre) and the postage due became 29 öre as marked with blue crayon.2x 1 öre, 2x 3 öre, 3x 5 öre and 6 öre adhesives on reverse, all cancelled Rödeby 4.10.1887. Attractive advertising cover opened up for display.