50 C. charity issue "Musica with new value surcharge + 20 C." with Type I overprint, vertical pair with inverted overprint, correctly rated multiple franking on letter from Ghyvelde 11.7.1940 to Dunkirk, arrival 12.07.1940 on reverse, perfect condition, expertised Calves, Dreyfus, Roumet and expert report Lothar Herbst VP (2025) "Condition is sound. These stamps are known in very small numbers, hence very rare. Multiple frankings with charity stamps, especially with inverted overprint, are extremely rare.", Mi. 1.700.-