"there is still a huge gulf between what is accepted as mainstreamn policy in the UK and what would be considered pretty radical in America"

I'm sure if we sat down and discussed issues we would find that there are mainstream policies in the U.S. that would be considered radical as well, but your point is well taken.

As it seems you have come from what many would consider a radical point of view to begin with, perhaps the main issue is one of common ground.   We've become a diverse nation with a line that has been drawn deeper and deeper in the sand. The idea of change will start at the far sides, but the actual change will occur in the middle. That is one area we need to heal - an understanding of each other and the ability to listen. I'm afraid that has been lost as we become wrapped in our own ideals and less inclined to accept that others see things differently.