It’s more sophisticated on this enclosed little island. I see it at work all around me, across the full age spectrum.
Individuals inherit cultural fragments, and rapidly, say by age 10, implicitly understand that the grandees with wealth are an inaccessible bunch. They just don’t quite know how many grandees there are, and just how inaccessible they are. Anyway, they project onto their futures this cliff-face, and they don’t even apply for those jobs - in fact, they probably never know they exist, nor which firms have those jobs.
So the system automatically pre-filters. The very smart students are given a leg-up, to an extent, but must learn the plummy accent in order to blend in. In a law firm, for instance, an upper class client risks being upset or worried if they’re dealing with a lawyer with a street accent. They will immediately presume, wrongly, ignorance, and hence menace to their capital.
It’s not just the language - in fact, the barrelling tone of voice, the ability to project, the capacity to engage and run a conversation, the ability in essence to control minds with your voice - that’s the key. The linguistic trickery sits on top of that.
Point is, there are 1,000 years of aristocratic history behind this. Any power system, to stay in power and control, must as an imperative control the decision-making, the capital, the people, the whole way of running it.
This is why entrepreneurs have a famously difficult time in the UK - it’s difficult to attract capital, because the capital sits with the aristo / banking class in the main, and if they can’t ensure control of the outcome of the entrepreneur, they sure as hell don’t want to fuel an emergent alternative wealthy class.
As a negative image, when you have a plummy aristo expressing themselves in street slang, it’s an automatic assumption they’re taking the piss, or so enamoured with their trust-fund-funded dope lifestyle, they couldn’t give a toss, and want you to know it.
The UK is very, very good with language. It’s just that not all its citizens know that.