Consider how RP Rose to Become a Prestigious Accent

            Modern RP can be described as "the speech of educated people living in London and the southeast of England." It developed from what was essentially a regional accent that acquired a unique level of prestige among the ruling and privileged classes in 19th Century Britain, particularly in London. No specific authority gave the accent that would become RP its special status. It seems to have developed as the consequence of its geographical position surrounding the capital, but can be found anywhere in the country.
             This accent has traditionally stood out above all others in its ability to link respectable social standing and a good education. Accents usually tell us where a person is from; RP tells us only about a person's social or educational background. Through time, RP came to symbolize a person's high position in society. During the 19th century, it became the accent of public schools, such as Eton and Harrow, and was soon the main sign that a speaker had received a good education. It spread rapidly throughout the Civil Service of the British Empire and the armed forces, and became the voice of authority and power. Because it was a regionally 'neutral' accent, and was thought to be more widely understood than any regional accent, the BBC adopted it, when radio broadcasting began in the 1920s. During WW2, it became linked in many minds with the voice of freedom, and the notion of a "BBC pronunciation" grew.
             In recent times the prestige associated with RP has fallen away. Today 'marked RP' is spoken only by members of the royal family and others from the upper classes. It is considered over-the-top by most people and a strong 'posh' accent will often attract ridicule. In order to communicate effectively and come across as 'normal', many former public school attendants retain some kind of regional accent or prefer to speak a form of Estuary English. .
             Today linguistists use RP as a 'standard' pronunciation of British English for study purposes and also by teachers of English as a Foreign Language so that schools can teach a standard form of spoken British English.