Would an A-Z be any good as a guide? I.e. London only extends as far as is shown in an A-Z? Or alternatively it is only in London if it commences with London Borough of..... I would say that if it isn't a London Borough then it isn't part of London - although might be referred to as part of Greater London.
I don't know tbh. I've though about it myself a few times, as we are on the borders of London - we live in SW but the kids school is in Croydon and our GP is in Mitcham, which are both Surrey although it still feels like London! I suppose saying London/Greater London works, but most people I know who live in Croydon would tell someone they lived in London rather than Greater London or Surrey.
Does this help ? Or this ? Both seem to include Richmond within London boundaries... Fwiw, I too would say Richmond is in Greater London and, since Greater London is London, IMO, I think you're both right!
Chislehurst where I live is also in this confused situation.
We are definately in Kent not London. However by virtue of being part of the London Borough of Bromley, we are part of London. We pay the London Authority Council Tax component, and we have an 020 phone number.
However I would never describe Chislehurst as being in London!