To chav and to hold
Whilst innocently asking young Tam whether the much-derided "chav" has flourished in the sociological niche that is New Zealand, interest prompted me to do a quick Google on the term, and lo and behold, its likely derivation is revealed on World Wide Words. Hey - VSX is educational!
it seems that the word is from a much older underclass, the gypsies, many of whom have lived in that area for generations. Chav is almost certainly from the Romany word for a child, chavi, recorded from the middle of the nineteenth century. We know it was being used as a term of address to an adult man a little later in the century, but it hasn't often been recorded in print since and its derivative chav is quite new to most people.
Other terms for the class also have Romany connections; another is charver, Romany for prostitute. Yet another is the deeply insulting pikey, presumably from the Kentish dialect term for gypsy that was borrowed from turnpike, so a person who travels the roads.
Did chavi die out, only to be reinvented recently? That seems hardly likely from the written and anecdotal evidence; what we're seeing is a term that has been in active but inconspicuous use for the last 150 years suddenly bursting out into wider popular use in a new sense through circumstances we don't fully understand.
"Through circumstances we don't dully understand" - bit of a cop-out there!
Shame, though. It's rascist derivation kind of puts me off continuing to use what was once a much loved term of unendearment.