You see, if I met someone who said they worked "in the city" and then it turned out they didn't actually work in the square mile (or near as dammit) I would think they were a show-off arse.
And thinking about it TBH I don't think I know many people who would just say "I work in the city". If the question is "what job do you do" then the answer is "I work in a bank" or "I work in a shop" or "I'm an accountant" and if the question is "where do you work" then the answers "in the city" or "in the city of london" or "near bank" or whatever are quite reasonable.
I don't think I've ever met anyone who would respond to the question "what do you do for a living" with "I work in the city" I would think they were a bit of a twat TBH.
It all conjures up visions of margot from the good life 