There was a good programme on BBC Radio 4 this week, in the Archive on 4 series. It'll be available here for a few days.
Melvyn Bragg discusses Received Pronunciation, and like all of his programmes on language, it's thorough, accurate and interesting. He's one of very few broadcasters who manage to talk about language without annoying linguists (at least, he doesn't annoy me). The programme is about the decrease in the use of RP in Britain. It covers a wide range of topics, including attitudes to accents, history of accents and so on. Well worth a listen.