45 C. definitive issue "Mercury Head" and 55 C. charity issue "Sanitary Service Monument" with hand-stamped overprint in Type I, proper franking on a letter from "Dunkerque 11. 07. 40" to Ghyvelde with a reverse arrival stamp dated 12. 07. 1940, flawless condition, certified by Calves, Dreyfus, Roumet and expertise by Lothar Herbst VP (2025) "The condition is impeccable. The stamps are known in very small quantities, therefore they are very rare.", Michel 1. 100.-