That's the thing about cigarettes.... they're addictive.
Not smoking during a 2/3 hour concert is one thing.. for 5+ hours is more difficult...
And in Hyde Park, it's a little more diffucult to enforce, isn't it. And also unlikely to affect PR or BR. They said it was for PR's benefit that they banned smoking on the tour which was largely indoor arenas.
Did they enforce the ban on the open air concerts they've done so far in europe - I think they've done some haven't they?