Hi all. Many years ago I recall a small construction in a local village that I was told was a British portable air raid shelter for a single person. I'm sure it was metal and had a single plank style seat in it. It was shaped like an old red post office box and had a large door which could be closed from the inside. Any ideas what they were called (if they were called anything at all) and what were they made of please?? Thanks for reading. Best wishes, Mark.