In my view, it's a personal confidence thing. People raised in a (UK traditional) working class family are bought up with lower expectations about what success

In my view, it's a personal confidence thing. People raised in a (UK traditional) working class family are bought up with lower expectations about what success they can enjoy in later life[1], compared to people raised in (traditional) middle class families. They will generally have less educational advantages eg: less pressure to read books, finish homework, do extra-curricular activities, etc. Getting to university will require harder work in a less friendly social environment. So when it comes to work, working class people will (in general) tend to have less confidence to negotiate a wage equivalent to their middle class colleagues doing the same work. Of course there's numerous exceptions to this on an individual level[2], but we're not talking about individuals here. [1] - anecdotal evidence: despite having an excellent academic record at school, the first question my Careers Advisor asked me was: "So which Regiment are you planning to join?" - which kinda sums up the sort of assumptions people made about me, based on my family's reputation and circumstances. [2] - me, for instance (I'm ignoring, for the purposes of this comment, the 7 weeks I spent in the Army).