The Royal We is where a monarch speaks not only on her own behalf, but on behalf of the country that she is rightfully entitled to make decisions on behalf of. The Chav We, on the other hand, is where you speak as if you are part of something you are only very vaguely related to, like a football team you support.
Alice: We were robbed of that goal! Fucking ref!
Bob: Stop using the chav we, Alice. You don't play football for England. Hell, you'd probably break you toe if you tried to kick a football.
Alice: Oh, shut it.