I am Northern and was down in London one day this week.
It's true that there seems to be more variation in London in what people are wearing.
There seemed to be an awful lot of people wearing contrived outfits. Dressing to be seen, rather than comfortable.
I used to work in a university, every year, there would be students turn up who dressed in whatever was fashionable. There would be a minority who "found" themselves and went off piste fashionable wise, kind of dressing to shock.
That's what London reminded me off, lots of those type of people along with the more run of the mill dressers.