30 C. special stamp "world exhibition 1937 in Paris" and 70 C. postal stamp "Merkur" with overprint in type I, correctly franked mixed franking on cover from "Ghyvelde 21. 7. 40" to Dunkerque with arrival postmark on the back from 22. 7. 40, photo expertize autumn VP (2016) : "the condition is perfect. The stamps are only in very small number of pieces recorded, so that they very rare are. "