Hmmm... That I do not know for sure. I do know that construction workers do occasionally adorn their hardhats with club logos, insignias, etc., and might wear them to football games, even en masse( group of fellas from work who might hold season tickets and identify themselves as such). Then there's the extensive tailgating that goes on pregame as a culture unto itself with its own customs and social mores... But this is really all speculation as I don't follow American football, though my Dad does.
Interesting thought(the idea that adorning hardhats at football was adopted from the British), but I imagine it might be a coincidental home-grown custom.
Thanks for that,as you say it could easily be a home grown thing,maybe the idea came over here from America..
There is a picture of a Rangers fan wearing a hard hat on the pitch at Newcastle,page 861 Mod to Suedehead.
Apologies to everyone for going so far off subject and I wont mention hard hats again.