We've had this topic a few times before :
here
and here
at least.
Here in Bristol and surrounding areas I've never been asked to remove my lid. The station nearest to me however has recently started asking me to get off the bike when filling up rather than sitting on it. They never used to have a problem with this, and despite being told it was 'company policy' other branches of the same company (Esso) don't mind. It's apparently because of scooter drive offs. As I'd just read the second thread above, and as the manager and I were being very polite, I asked if they would like me to remove my helmet. He said 'no, that's not a problem' .
Quite how getting off thie bike stops ride offs though, I can't really figure out.