What is the origin of the Received pronunciation English accent?

[Oliver109]

I think that even this basically standard accent has it's origins in west London and Middlesex where locals generally speak with quite a standard sounding accent, true Cockney was only really heard as far west as Hammersmith and as far north as Hampstead while beyond those areas the accents even among working class people do not sound especially strong.

[Tooting Carmen]

The speech of middle class Londoners.