As @Herbie says, above. Its a chip (fries) sandwich. It probably comes from the British tradition of Fish and Chip shops - you buy the fish and chips and take them home for Friday night tea. Buttered (or margarined) slices of white bread would be served as well. So the natural step would be to build a chip butty. You could say it was a working class tradition.
There is one place that was featured on Triple D called Primanti Brothers, I believe in Pittsburg, PA. They have opened 2 locations in south Florida. Just remembering that nasty lady at the one in PA, keeps me from trying the place.On some of the food shows - DDD for example - I see all manner of sandwiches piled with fries (chips) - including fish sandwiches. Just did not know what they were called across the pond. I have put store bought potato chips (crisps) on a sandwich.
Is it from Alsace? The Munster I've had is the sort you couldn't travel with on a train! Gruyere is certainly not smelly at all. Perhaps there is more than one type of Munster?I don't find it particularly smelly, but then again I don't think gruyere is smelly and some do apparently. It has an orangish color rind.