Well obviously if you're not reading anything about economics/finance then you won't have come across it. But if you do, which isn't difficult these days, then you would have come across the usage.
I'd probably agree with that. It's not what you first said though.
I'm still not sure that I'd agree with it being common knowledge outside of London though because well....Have you met the common public?
I'll be the first to humbly admit that until today I was completely ignorant of this.