I don't define myself at all. I think the English class system is hilarious and stupid (I lived abroad until I was 14 so saw how other countries do things). However, I understand it well, and understand also that working class folk are generally very proud to be working class, and would consider someone like me, with a professional career and university qualifications coming out of my ears, as anything but working class. I also subscribe to the notion that "words have meanings", and that you don't get to define them how you want. If everyone else in the country has a definition of the phrase that differs from yours, then you, I'm afraid, are the one who should consider whether you've got it right (and I say this fully aware that you are making a perfectly valid point).