Stan Carey has another fine post at Sentence first (“An Irishman’s blog about the English language”) discussing John Honey’s 1989 book Does Accent Matter? The Pygmalion Factor. He has some excellent quotes and anecdotes (one of which shows that Evelyn Waugh was horrible even as a teenager); I’ll pass on this excerpt about how people were pressured to talk “properly”:
There is little evidence that, in boys’ public schools at least, [RP] was systematically taught. New boys with local accents were simply shamed out of them by the pressure of the school’s ‘public opinion’. The prep schools, having pupils at an earlier, more formative age, were very important in this respect. In the decades immediately following 1870 there was a time-lag before non-standard accents died out among masters (and indeed headmasters) in the leading public schools. New appointees could be, and were, screened for accent. The boys’ reaction to that minority with ‘suspect’ accents who got through this screening depended upon their general effectiveness as teachers: a weak disciplinarian would find that his accent became another stick with which they would beat or bait him. In a popular man, respected for his teaching or sporting gifts, mildly non-standard speech forms were tolerated — even humoured — as part of the idiosyncrasies of a ‘character’.
Apparently an RP accent was “among the main criteria for being a British army officer in the world wars of last century.” Sheesh.