Country Life magazine has published an article reviewing the "U and Non-U" speech controversy 60 years since it raged in the 1950s after it was publicized by Nancy Mitford and Evelyn Waugh, inter alia, in the collection of essays published as Noblesse Oblige. Waugh's contribution first appeared as an essay in Encounter magazine (December 1955) entitled "An Open Letter to Hon. Mrs. Peter Rodd on a Very Serious Subject".
The article by Leslie Geddes-Brown opens with this background information:
The whole thing started with an essay by Alan S. C. Ross, Professor of Linguistics at Birmingham University, in an obscure Finnish linguistic publication. At the time, he stated that: ‘It is solely by their language that the upper classes nowadays are distinguished, since they are neither cleaner, richer nor better-educated than anyone else.’ How Mitford and her co-writers, Evelyn Waugh, John Betjeman (who contributed his already published poem How to Get on in Society), Christopher Sykes and ‘Strix’ (pseudonym of Peter Fleming, brother of Ian), came across the original is anyone’s guess. And I don’t think that Prof Ross actually listed all of the words unacceptable to the upper classes. I suspect – I would like to suspect – that Mitford made a whole lot up in the spirit of pure mischief. That would make the whole episode even more fun.
What follows are several paragraphs tracing words identified as having class distinctions in the 1950s and considering the current viability of those distinctions today. It concludes:
U distinctions largely died out, I think, with the advent of media types, such as cockney actors and photographers in the 1960s, who had accents. Instead of pretending to be dukes, we were more concerned to be born with a fruity cockney accent like Michael Caine, David Bailey or Twiggy. The accent of this century is, so far, either Estuary English or Mockney and, unsurprisingly, I don’t think we much care today whether someone is nobly born or an Hon. However, although the abandonment of silly class distinctions can’t be wrong, you can bet some other way of distinguishing the posh from others lurks in our psyches.