Been after this one for a while, and I finally managed to find a copy at a reasonable price -- the British WWII forgery depicting Hans Frank.
Hans Frank was a German lawyer and Nazi Party official who, upon the capture of Poland, became Governor-General of the Polish Generalgouvernement (the German administrative region covering occupied Poland). In this position, he was directly responsible for the atrocities committed on Polish citizens during the war, and as a result, he was tried at Nuremberg and executed after the war.
In 1943, the British created
this propaganda forgery depicting Frank.

The stamp design is an imitation of the 1941 Generalgouvernement 20 Groschen Hitler Head Issue
#77.

The stamps were airdropped to the Polish Resistance in January-April 1943. The Resistance mailed a small quantity of covers, each containing a propaganda leaflet, bearing the stamp and two genuine 2-Groschen stamps to various addresses in Occupied Poland.
The covers are rare (and even more rare with the original leaflet). The mint copies are less rare, but due to demand, the catalog value has risen quite a bit in the last 5 years.
Does anyone have an older Michel catalog that gives a catalog value? I have a 2012 Michel, but I'd like to find the historic catalog value in Euros or DM and my only old catalog is a 2007 with values in USD.