50 cent special stamp "a hundred years belonging Algeriens to France", vertical pair with inverted hand stamp overprint in type I as well above attached blank field, properly franked multiple franking on letter from Ghyvelde 21.07.1940 to Dunkerque with on the back arrival stamp from 22.07.1940, expertise Lothar Herbst VP (2018) : "the condition is perfect. The stamps are general only in very small number of pieces known, therefore are they very rare. Multiple franking with special stamps, to boot with blank field and inverted overprint, are extremely rare. ", Michel 3.000.- (former starting price 1000)