For example, I once travelled on the tube in London and on the underground in Liverpool on the same day. In Liverpool people were chatting with fellow passengers.
In London there was silence.
But yeah, there's no real sense of community in London, or in any big city really. Neighbours don't even know each other more often than not. There's pros and cons to this "anonymity" but it's nothing new nor exclusive to London. A lot of people actually like it this way.
I always liked old ladies fussing over my kids when they were small. The kids liked it too.