There is no "becoming" about it - America IS and always has been a lot more prudish than the UK. They also have higher rates of teenage pregnancy, abortions, STI's and eating disorders as well as greater demand for plastic surgery amongst teenagers. By studying 14 different nations we have concluded that there is a connection between these negative effects and being prudish.
I think Britain is becoming less prudish. In the ten years between us conducting two surveys (2001-2011) little had changed regarding the percentages viewing Naturism as either harmless or sensible (90%) and those who thought it was disgusting or criminal (9%). However, the number who described themselves as Naturists or nudists have increased 3-fold such that we now estimate that there are 3.7 million of us in the UK alone!
The press in this country are also moving away from the tiresome nudge-nudge, wink-wink style of reporting to a better, more sensible, approach. We still get occasional bad reporting, but most are Ok. A great improvement over a few years ago.
We have some way to go when it comes to sex education, but we have come on leaps and bounds regarding the acceptance of the sexual orientation of others. I believe America is yet to follow.
Curiously, America produces more porn than the UK, but then it has been shown that a puritanical (prudish) upbringing causes boys to have a greater interest in porn. I prefer the more relaxed, open and honest approach that is Naturism.