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Sorry jno, I expressed myself badly. What I meant was that there is a small portion of the platform which has a canopy over it; smoking is now not allowed there by the law of the land, even though it is open on three sides. The rest of the platform - by far the greater length - is completely open and is therefore not subject to the no-smoking law.
I merely wanted to know by what rule, bye-law or whatever SWT were banning smoking on this stretch as well.
As a non-smoker it does not affect me personally, but I am beginning to find distasteful the bullying that smokers are being subjected to, even in cases like this where nobody at all is affected by their smoking.