Wikipedia, the 'chav' answer to Encyclopaedia Britannica and OED, and thus an authority on chavs, has a long entry with many references.
Innit, Chav is defined "as a stereotype of certain people in the United Kingdom. Also known as a charver in Yorkshire and NE England "chavs" are said to be agressive teenagers, of working class background, who repeatedly engage in anti-social behaviour such as street drinking, drug abuse and rowdiness, or other forms of juvenile delinquency." (Alison Smith, BBC News)

Posts here suggest that the term has been extended to older humans than teenagers, or to anyone who is obnoxious and perceived as a lower form of humanity.

(Canadian, trying to understand English english as it is spoken there - and apologies to the Wikipedia contributors but I couldn't resist my little demon)