Clenched jaw?

The accent of one who has been through the elite school system in the UK is distinctive. The question is -- how can this accent replace the original accent of boys from all over the country who presumably have developed their speech patterns when they get to school?

Do we really want to replace the colourful accents that are the spices of any language? I was noting the previous discussion on the Irish accent, yet there are so many different Irish accents as there are English accents as there probably are in any country. I grew up in east Cork in Ireland and just a few miles away, across the Blackwater River in Waterford, the accents were entirely different. I have always marveled at how one language can be spoken, written and perpetuated in so many different colourful ways. Homogenized milk and language anyone?

I have to declare an interest here, in that I am the product of Eton College and am Irish. My accent (which I do not regard as stereotypically 'upper crust' - I think it is rather neutral) was acquired long before I went to school. I think you will find that most people who attend British public schools will come from families who themselves have been to public schools, and thus will speak 'RP'. I think we gather our accents from our parents/siblings/friends long before we ever get to school.

DFG

Is the U.S. equivalent a "lock-jawed accent"? From a review of the movie, "Mona Lisa Smile":

Joan (Stiles, employing a perfectly lock-jawed Groton accent) is mixed about marriage; she might want to go to law school, and Katherine might want to help.

I know it as a "clenched jaw" way of speaking, as Thurston Howell III (Jim Backus) spoke on Gilligan's Island. I never thought of that as an accent!

I think it can be an accent. I have a friend here who for years I assumed came from somewhere in England. He has a 'terribly upper-crust British accent' and definitely the whole 'clenched jaw' routine. I was astounded when he told me he was a Kiwi. However, he was raised by 'terribly upper-crust' English parents who clearly influenced his accent. I don't believe it's affected - maybe once in his life it might have been, but I think it's long since become an actual part of him.