By Richard Reeves
Presenter, Analysis, BBC Radio 4
The government says councils should be building more social housing - but can they avoid repeating past mistakes?
One of the five evils William Beveridge hoped to eradicate in his plans for the post-war welfare state was "squalor".
After the sacrifices of the Second World War, families should no longer have to endure cramped, damp homes provided by unscrupulous owners. The state would become landlord instead.
After falling out of favour during the Thatcher and Blair administrations, council housing is back on the political agenda.
The government is encouraging councils to start building again. Kate Barker, who has reviewed the housing market for Gordon Brown, is urging the Treasury to find £6bn to build a new generation of council housing.
As a small, heavily-populated island with strict planning laws, Britain is unable to supply decent, affordable housing to people on low incomes.
Social housing will remain a vital arm of the welfare state for the foreseeable future.
It has been a lifeline for people like Emran Shaheen. He has just moved into a housing association flat in south London.
Until recently, both his and his brother's family had been sharing a two-bedroom flat.
"I got married, had my wife there, when [my brother] got married, he had his wife there so we ended up being 10 people in one property in the end," he told me.
But before investing more in state housing, it is important to learn the lessons of the past.
The original mission of social housing was not simply to put a roof over people's heads, but to ensure that poor people were able to remain in the mainstream of society, rather than being distanced by their poverty; and to provide a secure base upon which people could seek work.
On both these counts, the evidence suggests social housing has been failing in recent decades.
Post-war Labour housing minister Nye Bevan argued for a social mix on council estates.
He aimed to replicate "the lovely feature of the English and Welsh village, where the doctor, the grocer, the butcher and farm labourer all lived on the same street - the living tapestry of a mixed community."
Until the 1980s, council housing was in fact embraced by a fairly broad swathe of the population.
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Since then, council estates have seen increased concentration of social problems, in part because of a shift towards providing homes on the basis of social need.
Professor John Hills from the London School of Economics is Britain's leading analyst of social housing.
He is worried about the consequences of this policy.
"If you had started saying what we want is housing provided for people in greatest need, I don't think anybody in their right mind would have thought let's build it all in big estates and put all those people together in the same place."
Most working-age adults in social housing are out of paid work. Seven out of 10 tenant families are in the bottom two-fifths of the population in terms of income.
Social housing tenants are twice as likely to be unemployed and twice as likely to be lone parents as those living in private rented accommodation or their own homes.
"You are then creating a situation where one group of people, who end up with difficulties in the labour market to start with, are away from contact with the run-of-the-mill services, jobs, knowledge about jobs that one would expect in the rest of society," says Hills.
"From the point of view of society as a whole, the idea of walling away one group of people from the rest of the society, so that people become invisible to the mainstream, is not a healthy part of the political process."
If social housing is - for good reason - going to be focused on the most needy, the only way to avoid vast monoculture estates is to build "mixed tenure" developments.
Housing Associations - private but not-for-profit providers - were leading this charge until they were hit hard by the downturn in the owner-occupied sector, which helped fund these developments.
But there is no reason why local authorities should not show more imagination in the way they construct estates, and go for a better social mix.
One of the most controversial and sensitive areas in social housing policy is security of tenure.
This means that once you have got a council tenancy you can keep it, regardless of any later changes in family size or income. In theory, you can go from an impoverished single parent of five to a millionaire lottery winner and keep your council flat.
One of the main arguments for this policy is to ensure that social housing tenants are not put off going into a job.
The fear of many policymakers is that if people fear losing their home if they succeed in getting paid work they will be less likely to look for a job.
Alan Walter, of Defend Council Housing, wants to ensure social housing tenants do not face any more insecurity.
"What people want is a home, not just somewhere to lay down their head for a few nights," he says.
"There is something that I find really offensive when you have politicians talking about council housing as if it is just a short-term fallback for those in desperate need."
On the other hand, security of tenure does not appear to having the positive effects on levels of employment that the economic textbooks suggest it should.
Social housing tenants are significantly less likely to move into paid work than private renters.
The goals of social housing remain salient: to provide decent, affordable homes for those unable to secure them, to allow children of low-income families to grow up in the mainstream of society, and to provide adults with a platform upon which to build independent lives and careers.
The trouble is, social housing is not delivering on its promise. On current trends, it risks becoming anti-social housing.
Richard Reeves is director of the independent think tank Demos. He presents Analysis: Anti-social Housing on BBC Radio 4 on Thursday 26 February at 2030 GMT. Or subscribe to the programme's podcast.