In his recent guest post about the language of the theatre, Ben Trawick-Smith mentions the privileged position of Received Pronunciation. RP, he writes, was virtually de rigueur in English theatre “until it became apparent to (some) Britons that dialect prejudice is as bad as any other”.
An RP accent, even a modified one that combines it with regional qualities, has prestige because it implies a certain level of education, social status, prosperity and perhaps political power. Centuries ago it was the accent of the courts and high society in London and the home counties; people moving there to advance in life often adopted it as their own.
Later, RP became the accent of public schools and the BBC, which strengthened and stabilised its status as the “standard” form of English speech. It was (and remains) linked to class consciousness. In an excellent historical essay, The Rise of Prescriptivism in English (PDF), Shadyah A. N. Cole writes:
As the middle class increased in numbers and in wealth, they desired also to have the manners and education of those above them in social status, or at least the appearance of them. … When appearances failed to signal the distinction between classes, manner of speaking including pronunciation and grammar were found to be useful in making the distinction.
Cole argues that this desire for “a veneer of educated speech”, along with “a lack of confidence in their own variety of language”, set the stage for the development of prescriptive grammar. Nowadays RP is less exalted, and regional dialects are encountered more often in the media. But where there’s cultural difference and social inequality, there will also be prejudice and snobbery; terms like feral underclass were used to describe rioters in England earlier this year.
Ireland, though a relatively small island, abounds in dialectal variation. Here, as elsewhere, accents mark geographic identity (and social standing, to a lesser degree), and people sometimes embrace new dialects to distance themselves from areas or attributes they don’t wish to be associated with. Raymond Hickey calls this “linguistic dissociation”, and in his book Dublin English he discusses the phenomenon of “Dortspeak” in some detail.
Dortspeak is a homogenised middle-class accent that spread from Dublin 4 (= a postal district of Dublin, also known as D4). It got its name from the D4 pronunciation of Dart (Dublin Area Rapid Transit, a commuter train service), and has been described as a mixture of Irish English, British English, and the American English heard in TV shows like Friends. Less flatteringly, it has been called a “strangulated middle-class mid-Atlantic airhead accent”.
Dortspeak is widely scorned, and heavily satirised in journalist Paul Howard’s fictional creation Ross O’Carroll-Kelly, who for example pronounces (and spells) start as “stort” and right as “roysh”. Professor T. P. Dolan says people are switching from local accents to the D4 accent “because it is seen as the way to get ahead” – by adopting it, people aim to cut an obvious tie to their background, whatever it might be.

Stan:
Accents are fascinating, because so many substrates exist, down to the idiolect. In the US, RP remains a prestige accent; in our “classless” society, the closest we had was the Mid-Atlantic accent, prevalent in the cinema of the thirties and forties. General American, on television and radio, is our plain vanilla answer to RP. Re your comments about Dublin accents, in New Jersey, linguists say we have only two accents, divided by our proximity to New York or Philadelphia. I reckon we have at least a half dozen recognizable accents.
Marc: Yes, there are as many accents as there are speakers; but as you imply, it makes sense to categorise them into broadly recognisable varieties. Growing up watching American films, I got used to seeing English accents, particularly RP ones, used as shorthand for either sophistication or evil! Lynne Murphy has an interesting post on US attitudes to UK accents. One study found that “people who’d lived at least three months outside the US rated the English accent significantly lower than people who’d only lived in the US.”