One thing I forgot to mention in yesterday's post on Estuary English was mockney (sometimes written with a capital M), which is similar. The word itself is a pun on mock and Cockney and refers to a form of English, or an accent, which is put on by someone who really has a much 'posher' or more middle-class accent. People adopt mockney in order to appear matey and appeal to the wider public, who generally have a negative view of the cut-glass vowel sounds of the Home Counties.
The word mockney can describe the speaker as well as the accent. A mockney, therefore, is someone who exaggerates features of Cockney - glottal stop, saying f instead of th (I fink), h-dropping at the beginning of words, vowel lowering (saying sparra instead of sparrow) and tags at the end of sentences (know wha' I mean?). The celebrity chef Jamie Oliver is a mockney. He grew up in a middle-class Essex household, but affects a working-class mockney accent. Another mockney is the film director Guy Ritchie, who makes films about London criminals, but is himself from a very upper-class background (his mother has the title Lady Leighton).
Mockney has entered the Oxford English Dictionary this month (March 2009).