In a letter of 1955 to Nancy Mitford about her article “The English Aristocracy,” later included in Noblesse Oblige, Evelyn Waugh makes the link between idiosyncratic linguistic preferences and social class:
I wish in your Upper-class Usage you had touched on a point that has long intrigued me. Almost everyone I know has some personal antipathy which they condemn as middle-class quite irrationally. My mother-in-law believes it middle-class to decant claret. Lord Beauchamp thought it m.c. not to decant champagne (into jugs). Your ‘note-pager’ is another example. I always say ‘luncheon’ but you will find ‘lunch’ used in every generation for the past 80 years [by?] unimpeachable sources. There are very illiterate people like Perry Brownlow who regard all correct grammar as a middle-class affectation. Ronnie Knox blanches if one says ‘docile’ with a long o. I correct my children when they say ‘bike’ for ‘bicycle’. I think everyone has certain fixed ideas that have no relation to observed usage [emphasis added]. The curious thing is that, as you say, an upper class voice is always unmistakable though it may have every deviation of accent and vocabulary.
The text is from The Letters of Evelyn Waugh, edited by Mark Amory (Ticknor & Fields, 1980).