It's designed for the Hyacinth Bucket's of the world - in Britain, only the middle classes care what class they are perceived to be.
Everyone else (working & upper class) just get on with their lives and buy/wear/consume what they like.
The middle class lot are desperate to not be lumped in with the working classes so tend to cling to lifestyle or ideologies and wear them like a badge.
(Massive, huge generalisation but pretty much how the Telegraph have approached this quiz tbh - I'm sure most middle class people couldn't actually give a toss either and are just living their lives like everyone else!)