"Received Pronunciation was invented"

How so?

It's not the natural evolution of a regional dialect coming to prominence but rather the conscious consensus of a geographically distributed social stratum.

Interestingly, the sociolinguistic literature shows that such a consensus is strongest among an aspirationally upward-mobile social group rather than the already social elite. In other words: The aspirational middle class make a big effort to speak how they think the upper class speak in hopes of joining them one day.