This is an interesting conundrum. They are definitely NOT chavs, and would never associate with real chavs. ('Pikey' is an adjective for something chav-esque, but a little less specific. Simply means 'vaguely lower class and 'local'). Blake Fielder-Civil is not a 'chav' (the double-barrelled name is a dead giveaway). Nor is Winehouse. They are upper middle class London kids who adopt their own version of a 'chav' accent to sound tough, and 'keep it real'. But they get it totally wrong. There is an entire subculture of British public (i.e. private) school boys whose attempts to sound tough and working class, while failing horribly, also ring out like a siren announcing 'beat me! beat me senseless!'. They have created a faggy, hybrid accent that would never fool a chav, and invites swift, painful correction.
Now if it were Charlotte Chuch doing this I might give it five stars. Let's get some videos of her and Miley Cyrus paintballing immigrants and destroying mailboxes.