Cathy and Reg have everything to live for: he has a well-paid job, they have three healthy children and a modern home. But when Reg loses his job, they find their life spinning out of control. Evicted by bailiffs, they face a life of poverty, illegally squatting in empty houses, sleeping in shelters and fighting to keep their family together.

Watched by 12 million people - a quarter of the British population at the time - on its first broadcast on 16 November 1966, Cathy Come Home was a defining moment in British television history. Controversial, moving and brilliantly acted, it provoked major public and political discussion and challenged the accepted conventions of television drama. In 2000, a poll of industry professionals conducted by the British Film Institute placed Cathy Come Home as the best British television drama of the 20th century.

Housing Problems is both a propaganda piece and a document of optimism. With its iconic image of new flats rising behind an old row of slum terraces in Stepney, it shows what has been done to improve living conditions by the most 'enlightened' local authorities and planners, and provides an exhortation to others to follow suit. Rather than merely asserting the necessity of new housing, it uses the voices and stories of working class men and women to demonstrate the slums' dreadful conditions, and the benefit of the new estates.

Its method - ordinary people talking straight to the camera about their lives - was an innovation in documentary, though to a modern viewer the rehearsed words sound stilted. A more serious note of condescension might be gathered when the narrator tells us that slum-dwellers 'quickly respond' to their improved living conditions by becoming more hygienic themselves. (...)

Finally, there's a chilling pathos in the filmmakers' hope that in the next ten years the worst of the slums would have been cleared. By 1945, the Luftwaffe had indiscriminately destroyed large areas of working-class housing, and Britain faced a new and rather more desperate housing problem. (Danny Birchal / BFI)

Homelessness is as big an issue now as it was in 1966. We need to recognise that it is the economic system itself, capitalism, that causes people to be homeless. It's about time we started to look at this, the fundamental issue. (Ken Loach, 2011; at a debate after a Cathy Come Home screening).