While Pete has a point ("English liberals also hate working class") that there is a very patronizing undercurrent of distaste for the working class among the UK left (though liberal means something else in the UK -- the social middle-ground with libertarian economics), it's a long stretch to say that Chav equals working class. It's a more specific term than "white trash". It would be a bit like saying that "soccer mom" is a synonym for "middle class" in the US (whereas lots of middle class are not soccer moms). Sure, Chavs are a subset of the British underclass -- ignorant, uneducated, violent, with a particular fashion "uniform". Chav is said by some to mean Council Housed And Violent, though I think that was invented after the fact.