After Dunkirk the Germans collected up the equipment left behind by the Brits and equipped some french police units loyal to the Germans. The Brits left a lot of stuff behind. I saw a picture of this unit many moons ago. It wasnt a military unit but a Gendarme group that looked out for local trouble makers. While it could be anything, there is a chance it is a Occupation Gendarmerie helmet or something of the like. If i find the picture ill post it.