One by one, many of the working class neighbourhoods of London have been invaded by the middle-classes—upper and lower. Shabby, modest mews and cottages—two rooms up and two down—have been taken over, when their leases have expired, and have become elegant, expensive residences ... Once this process of 'gentrification' starts in a district it goes on rapidly, until all or most of the original working-class occupiers are displaced and the whole social character of the district is changed.