This is tosh.
It has me down as West London.
I'm not having it.
A few years ago I was visiting friends in Toronto.
I met with an Englishman. A thespian and something of a recreational linguist.
We chatted about this and that.
Within half an hour or so, by my accent, he'd pinned me down initially to South London and, a few minutes later, to Southeast London.
It was quite uncanny.
As well as being accurate.
Other than the year I spent living on Corfu, and 8 years in Harrow, I've spent the rest of my life in Londres Sud.