Teaching dialect, sociolect and idiolect is fun.
Once, in an overseas school (overseas I more or less use RP), I taught a boy from the area in Northumberland I used to teach in. We greatly amused the other students (German,Swiss, French, Spanish, Russian) with our chat (Ah divvnt kna, Howay wi wa).
I also knew a teacher who was marked down in a lesson observation once for her regional accent. Her observer was roundly castigated later for it. It was total snobbery on the part of the observer.
To think that London, or anywhere else for that matter, does not belong to any one demographic
People eating and drinking on the go