I felt bad that I'd missed 'booth'. I was talking to my daughter about it last night, saying I wished I'd a picture of Boothamgate in York (the street where the market booths were set up in the fourteenth and fifteenth centuries... sort of suitable!). She said "Well why don't you take a picture of..." So this afternoon, I did.
That's a traditional red phone box - which is pretty much a booth, I reckon!
And yes - the phonebox and the letter box are fairly much in the middle of nowhere - there are about five houses within walking distance.