The first part of the 20th century saw rapid geographical growth outside the County of London through suburban expansion into Essex, Kent, Hertfordshire, Surrey and Middlesex. Middle-class residents relocated to less built-up districts, seeking lower density suburban housing, while ‘Homes for Heroes’ were available for soldiers returning from war. The growth of transport networks, including the electrification of commuter railways, extension of the London Underground to the north and construction of arterial roads including the A406 North Circular, supported the expansion. The building of housing estates, and the relocation of industry and manufacturing facilities outside the city also led to working-class migration. Eventually, urban growth was restricted under the Green Belt Act 1938, but the suburbanization of London – particularly interwar expansion – meant that by 1939 more than half of Greater London’s population resided outside of the County of London.
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