Plotlands? The London Grid for Learning Redbridge page explains:
During the 1890's, agriculture declined because of a series of poor harvests and cheap grain imports from America. Fields were sold off to land agents, who auctioned them off as small plots.
After the First World War, the British Government promised 'a land fit for heroes' and building one's own home in the countryside was encouraged. Later, the Depression of the 1930s drove people to settle in the Plotlands and build themselves a place to live.
Later. The film has at last appeared on Youtube.