1 Fr. postal stamp with overprint in type I as correctly franked single franking on cover from "Dunkerque 2. 7. 40" to Bourberg with reverse arrival postmark from 3. 7. 40, in perfect condition condition, signed Zierer and certificate with photograph autumn VP (2014) : "the condition is perfect. The stamps are only in very small number of pieces recorded, so that they very rare are. The postmark "Bourbourg" is very rare. ", Michel 1. 000.-