Blimey - this brings back a few memories.
Yes to Stanley Green protein man - used to see him most days as I worked near Oxford Circus. As a very naiive teenager in her 1st job then I actually used to find him a bit scary!
Am also old enough to remember Bourne & Hollingsworth department store in Oxford Street, Peter Robinson at Oxford Circus, several branches of the very good value Stockpot dotted about the West End, Wendy burgers (for lunch!), the very tacky Hippodrome on Charing Cross Rd (was aghast at the revoltingly ugly and "old" men in there who had terribly young women draped all over them) plus as others have said, the days when Foyles was a right hotch potch of books, with, IIRC, a system where you didn't pay straight away but an invoice was sent via some overhead air system - sorry, can't think of a better way to describe it - to some other location in the building where you went and settled your bill. Can't really remember that in detail but it seemed very weird.
Can also remember a time when the now beautiful and flagship John Lewis in Oxford St was actually rather down at heel and tatty ..... grotty carpet patched up with duct tape in the perfume department for example.
And here's a very long shot - can remember having lunch in a teeny tiny "caff" in Marylebone Lane which sold real old school style food - practically school dinners, like liver and bacon, for what seemed like pennies. You were literally sitting on top of each other though and even back in the 80s it seemed very old fashioned. Don't supposed it's there now but would love to put a long forgotten name to it.
Also bemuses me how perceptions change - used to do day release study from work in a college near Aldgate East and was petrified about walking there and back and using the tube round there because it seemed so sinister (or maybe that was my imagination ?) and "rough". Now - if I go to London at all am happiest walking about near Brick Lane, Spitalfields, Hoxton now it's all been trendified.