50 C. Mercury Head, horizontal pair, "Occupied Territory Northern France" overprint type I, correct multiple franking on letter "Ghyvelde 3.07.1940" to Dunkerque, arrival 4.07.1940 on reverse, perfect condition, expertised Grobe, Lothar Herbst VP expert opinion (2023): "Condition faultless. Stamps known in small numbers and therefore rare.", Mi. 600.-