London is exceptionally economically polarised because of our housing policy. About 40% of people in inner London live in some form of subsidised social housing. This creates a "hollow middle" in the income distribution - people who are priced out of London because they can't afford market rents, but earn too much to qualify for social housing. You can't really be too poor to live in London, but you can be too average.

https://www.ons.gov.uk/census/maps/choropleth/housing/tenure...