Silly notice

A non smoker myself, I do try to avoid smoky places.
However, I also collect pictures of silly notices, and this one is near to a Nottingham city tram-stop at the Lace Market.
It is on a lamp-post by the tramstop on a wide city street with a pavement that I paced out as being 15 yards wide.
So my question is "what actually constitutes "smoking at this tram stop"? I
How close does one have to be to the actual tram stop to be in breach of the law?
It is utterly daft and unenforceable, the sort of thing that just brings the law into ridicule and contempt.... and why this one tram stop in the entire city?
I know of no other that is similarly marked. End of rant!