Whitespirit66 said:London is another country, where if you have money, you will be able to insulate yourself from a lot of what goes on. Most of the sensible 'Londoners' have emigrated to the south east or elsewhere.
The first time we went to london was 1986 and, since this was a weekend coach trip, we were in the 'good' bit, the London tourists come to see. Even so, I was taken aback by all the obviously foreign accents. We were there a whole day before we heard our first cockney cab driver. When I mentioned this he replied, with typical cockney wit, "I got out of London at the first whiff of curry".
Now I've got nothing against those foreign workers, all of whom were doing a perfectly good job, but they confirmed the hypothesis of the original post: even back then, London wasn't English. Our more recent excursions into 'the smoke' have come about since our daughter went to Imperial College. This, of course, means that she's insulated from the sleazy side of London life but it didn't take her long to work this out because she declared that "everything South and East of the centre is no-go".
So what of the remaining quarter? Well, we drive through it to get to her flat, we see the burnt out houses dotted along the North Circular and we think "If this is the 'decent' quarter, what in God's name is the rest like? "