"It is impossible for an Englishman to open his mouth without making some other Englishman hate or despise him." GB Shaw, "Pygmalion"
We are not unfamiliar with this in America, where southern accents remain a moderate obstacle for those who would be thought intelligent. The phenomenon has more variety in England, and came up in our discussion about CS Lewis's declining popularity as an apologist there, at least partly due to changes in accent over decades.
NYC-area accents are considered grating, and Western or Midwestern accents, particularly if they are rural, are also disfavored. Hyphenated-American accents are also considered signifiers of those who are fresh off the boat and/or too lazy or stupid to learn how to get it right. My grandmother's family was Swedish and tried to quickly shed all patterns of speech that would brand them as less American, less intelligent. Her husband's Scots-Irish family were schoolteachers after having been in Londonderry a hundred years, and were apparently the sticklers for correctness typically associated with that breed.
That is my culture. That is my background.
But it's wrong. Accents might tell us something about a person's culture, but not his character or intelligence. Displaying a favored accent, or the standard midamerican dialect is an advantage in many situations, and specific situations call for extremely strict rules of usage. Those aren't quite the same as correctness, however. We've been over this before.
The image I use to remind me of this is visiting a foreign country, where the varieties of accent would not be heard or understood by one such as I. I think of one person in Elbonia describing the speech of another citizen: "Hahaha, you can tell he is a stupid Mountain because of the way he pronounces his 't's!' We sophisticated Valleys do not do that, because we have been properly educated."
Thus, it seems amazingly ignorant to me that the English cannot simply shrug at Lewis's accent and tone and think - "Oh yes, the old accent. Funny how things change" and just move on. But it doesn't work that way, not for any of us, with accents that we actually encounter and have cultural associations with. Those enter straight to the cultural centers of the brain and can only be overlooked with effort.
The effort is worth it.