I am bit of a pillbox fancier, interesting little structure and thanks for sharing. B & W conversion works well, but overall its a bit too central and posed for me, bright white sky through the slit also doesn't help either.
Can see from the sky how poor the light was and reckon you have done well to rescue anything from the day. Had similar conditions myself last week when I went for a camera laden walk, just gave up in the end and went home for a cuppa