This tiny thing is in my hometown; I’d walked past it many times in my life and assumed that it was an old brick bbq nothing more….
You see what I mean?
Closer inspection does reveal that it is in fact a very small air raid shelter. It is about 2m x 3m, full of rubbish and spiders, there looks to be some evidence of electricity in there too and some pencil scrawl on the door which is indistinguishable!