I seem to recall a British friend of mine telling me about the time that they tried to bring American football to the UK, some sort of Cup or Bowl of some sort, and after a while the US said 'um, you know what, I think we're okay not going overseas' and basically chickened out because all the UK teams were made out of guys who grew up on rugby, and they played mean. I don't recall more details, but something along those lines has been tried, and of course America wimped out.