If there is one aspect of housing policy that enjoys something approaching a consensus, it is that we should no longer build monolithic estates of social housing which concentrate large numbers of vulnerable or poor people in a single neighbourhood.
We know that such concentrations have failed and are failing in a host of different respects: they are difficult to manage in housing terms; it is hard for residents to break into the labour market; patterns of deprivation can be replicated in local schools, maintaining a cycle of disadvantage; services are often poor; and high levels of crime and antisocial behaviour are not uncommon.

Multi-tenure developments are, of course, not without their problems, and need different skills and resources to manage effectively. Nonetheless, most of us would surely agree that the closest to the ideal is a "street scene", or its nearest equivalent, that renders it impossible to tell from the outside the tenure of the occupant within. My own street of north London three-storey terraces, for example, includes council and housing association properties, owner-occupied flats, a few properties owned in their entirety by a single household and some privately-rented homes in multiple occupation (when out canvassing I am occasionally confronted by 15 doorbells on one front door, none giving the slightest indication as to which elector might be connected to which bell). My neighbourhood has its full share of the difficulties associated with high mobility, ethnic diversity (70 languages spoken in local schools) and social deprivation, but it is still delightful to be free from preconceptions based on how each person pays for the roof over their head.

However, having reached this conclusion, we then need to examine the policy implications. This is the hard bit. Whereas it makes considerable sense to ensure that future developments are mixed tenure, many of our neighbourhoods are currently too rigidly segregated. In London, whole boroughs such as Southwark, Newham and Tower Hamlets are characterised by high unemployment, poverty and low pay – mostly problems concentrated within the social housing sector.

If poorer areas are to diversify, then wealthier areas have to diversify as well. Mixed communities can’t be a requirement in one area, but uneconomic in another

The catch, however, is that the drive to diversify poorer neighbourhoods does not in itself reduce the number of people who are vulnerable, in housing need or simply poor. The government has achieved an extraordinary amount in five years through good economic management – full employment, improved benefit levels and in-work benefits such as working families tax credit – but it would be quick to accept that there is still a very long way to go. In London, poverty levels have not dropped in line with the rest of the country, and homelessness has in fact increased in recent years with the rising population and long-term failure to increase housing supply. So we have to confront a tough reality: if poorer areas are to diversify, then wealthier areas have to diversify as well. Mixed communities can't be a requirement in one area, but uneconomic in another, unless we are prepared to accept a continuing and unacceptable level of homelessness.

There are two tests that will determine whether this nettle is to be grasped. Firstly, advocates of rent restructuring and "shopping incentive"-based housing benefit reform need to explain why those making a living in high-value areas should be effectively penalised for doing so. We want and need affordable housing for lower-income households and social housing tenants in high-value areas, both to ensure a wide spread of mixed communities and to meet labour market needs. Second, at least some of the hugely welcome boost to housing investment announced in the comprehensive spending review needs to be directed to high-value areas of housing shortage as well as to the planned growth areas. We know only too well from the experiences of some northern councils that you can't make communities sustainable if people don't want to live there.