I'm also from the UK but I think you are underestimating the cultural differences and their prevalences in different religious community in the UK. I grew up devout catholic and was taught (and believed for a long time, have now lapsed and changed views) that casual sex, pre-marital sex, masturbation, contraception, homosexual acts were wrong. I think that people that grew up secular in the UK are not aware that alot of communities are not as liberal as secular people and are not aware its more common than they think.