I am not surprised that state schools are not a mono culture.
My DS is young and I would rather he had a sense of who he is and where he is from and be able to feel that he fits in before being subjected to multi cultural systems (I am not being racist here - many independent schools are culturally far more diverse but socially far more cohesive).
I do want my DS to be in an environment which shares a wrok ethic, which develops good manners, good speech habits, politeness etc. I alsowant him to to develop in a culture where his abilities and skills are not scoffed at. Where as I said, he will be the possessor of the wrong culture because we do not watch BGT or I'm a Celebrity - Get me Out of Here.
( we may not even watch TV in our house sometimes).
Whilst there may be a few DC in a bog standard comp who may share his "culture" they will be far fewer ( in fact, in my own case, possibly none)
Its about simple things and more complex ones.
I have worked in challenging schools and in "bog standard" ones. I have also worked in some of the elitist of places. The differences are in the small things often. Its the small things that matter though.
I am not telling others to educate their own DC as I would mine, but I do not see why I should be criticised for my views and lifestyle either