Via Google Maps

That's Clement Attlee's cabinet. In 1947, the Attlee government introduced the Town and Country Planning Act, which made it illegal to build anything without planning permission. Their plan - masterminded by Aneurin Bevan - was that the government would provide most new housing, and new private homes would be very strongly restricted. Meanwhile, big, successful cities such as London, Oxford and Birmingham would be surrounded by green belts, in which it is almost impossible to build anything. They really hated urban sprawl.