Why does UK have a hierarchical society?

What is the origin, what qualifies the people into classes, how does the classes affect peoples lives? I used to live in the UK but was never conscious of it. But I realized the differences in pronunciations. How can there be clear differences in pronunciations when people speak the same language in the same region? Are there possibilities of transfers between the different classes? Please give me details about it. Thank you.|||This is ubiquitous in human society - we're a social, hierarchical species.