RP is a young accent in linguistic terms. It was not around, for example, when Dr Johnson wrote A Dictionary of the English Language in 1757. He chose not to include pronunciation suggestions as he felt there was little agreement even within educated society regarding ‘recommended’ forms. The phrase Received Pronunciation was coined in 1869 by the linguist, A J Ellis, but it only became a widely used term used to describe the accent of the social elite after the phonetician, Daniel Jones, adopted it for the second edition of the English Pronouncing Dictionary (1924). (British Library)
"All RP speakers speak Standard English. In other words, they avoid non-standard grammatical constructions and localised vocabulary characteristic of regional dialects. RP is also regionally non-specific, that is it does not contain any clues about a speaker’s geographic background. But it does reveal a great deal about their social and/or educational background."
Indeed many commentators even suggest that younger RP speakers often go to great lengths to disguise their middle-class accent by incorporating regional features into their speech.
"As well as being a living accent, RP is also a theoretical linguistic concept. It is the accent on which phonemic transcriptions in dictionaries are based". (British Library)