What is Standard English? There is a common definition that it is nothing more than the mixture of RP and UKSE. However, there is no longer an unwritten law that Received Pronunciation should be closely connected with the upper-class or highly-educated persons. It has changed much and now even politicians tend to treat some non-standard features as standard ones.
That is why the examples of Tony Blair, Simon Reeve or Kate Nash show that the Received Pronunciation accent is changing and Estuary English (cockneyfied RP) slowly becomes the new standard accent. Even the prestige of the old way of speaking has lost its importance and starts to be perceived as affected and even, in some situations, rude. The BBC Television, which has always been the indicator of the standard way of speaking, prefers to use the cockneyfied version of RP. It will be inevitable for Received Pronunciation to meet the social expectations and evolve in this constantly changing world (Przedlacka 2005, 18).
The new Standard English will, probably, include more and more Cockney features, as they become, one by one, less stigmatised. It will surely take some time for RP to change (especially for its more conservative variants – let’s remind RP is not a monolith), but after several decades these “posh” features of speaking should disappear. In the perspective of the whole 21st century, RP can change so much that it will have nothing to do with the older versions of the accent. As a result, the name itself can lose sense. Cockney can also modify and as John Wells claimed: “Maybe in another two hundred years the posh form would be [‘f??s] and the Cockney vulgarism would be something else again, I don’t know,[‘f??s]”. Of course the change of these features is not so certain. A lot will depend on the social structure of the Great Britain, future important events and teenager trends. However, in today’s Great Britain, where social gradation is very popular and there are still royal and noble ranks, the clash between RP and Cockney has got one more dimension. By the change of the RP, the lower- and the middle-classes can symbolically win their last battle for equality as RP will finally democratise itself. Politicians and the royal family will not sound so “posh” and strange any more. They will speak just like the rest of the society. Beside the fact that it is, of course, a prognosis, it can become true.
Buy my e-book "British Accents: Cockney, RP, Estuary English" http://www.przegladdziennikarski.pl/jezyki-obce/english/e-book-british-accents-cockney-rp-estuary-english/