And the way - and crucially the location - in which UK residents live and earn their crust must be radically re-thought to prevent some areas of the country becoming ghost towns, they say.

Short of investment in jobs, infrastructure and regeneration, people are moving south - and no-one is coming to take their place.

The demands for housing available at less than the going market price have fallen correspondingly in some areas of the north, and shot through the roof in the south-east.

Office of National Statistics figures show that the average number of households leaving the north-east, Yorkshire and Humberside every year between 1991-1993 was 9,500. By 1997, that figure had jumped to 23,500.

Conversely, the average number of extra households moving into the south of England from other areas of the country every year between 1991-93, excluding London, was 46,200. By 97 the influx had totted up to an average of 69,500 a year.

A report by the Joseph Rowtree Foundation and the Chartered Institute of Housing investigates housing needs across the country.

Department of the Environment growth projections indicate that the UK needs 3.8 million extra homes - in both the private and social (local authority and housing association) sectors - in the next two decades.

People on the move

David Fotheringham, spokesman for the Chartered Institute of Housing, said: "We wanted to investigate the issue of the need for new housing - while trying to marry it up with a decrease in demand for social housing in some areas.

"What has come out of the report is just how complex the situation is."

He said that demand for private housing in the north is still fairly strong, but that another emerging picture was one of emptying estates in certain areas of the north of England.

On top of a lack of jobs, council houses can also be poorly maintained.

Mr Fotheringham said: "In some areas the houses are in poor condition and need investment, and in some cases demolishing altogether.

Demographics have changed

"People don't want to move to these areas, and social exclusion issues arise as all but those who really can't afford to be elsewhere move out."

It was Margaret Thatcher who introduced the sale of council houses, in her desire to increase home ownership levels.

But a decade after her political demise there's still a national dearth of homes to call one's own.

And the demography has changed - the kind of homes that are now needed above all others are small, built for just one or maybe up to three people.

Given that an average street in the suburbs contains about 20 semi-detatched houses, the impact of that figure in both environmental and psychological terms is evident.

Leaving the suburbs for homes in the country

Of those three million homes, not all will be newly-built. Some will be created out of existing buildings - the ubiquitous conversion.

The bulk, however, will be constructed at sites across the country, according to regional quotas set by central government.

Where those properties will go has been a matter of intense speculation, and the report's findings will pose big problems for planners.

"The government is going to have to address this issue. If it is allowed to continue indefinitely you will see the disintegration of communities in some parts of the north of England and other parts of the country," said Mr Fotheringham.

"The problem is self-perpetuating," he added. "Companies see that their biggest markets are in the south, and so will locate in the south, so all the jobs will be in the south. Intervention is required."

Making city life more appealing

Investment will have to be made at regional levels, he said, to provide long-term jobs, job retraining, and reasonable housing conditions.

Plans to encourage the steady stream of city-leavers to plant their roots back on urban turf are also due to be launched by the Urban Task Force next week.

Led by architect Lord Rogers, the task force has been looking at ways of making city life more appealing. Their report is expected to address the ever-expanding concentric circles of commuters surrounding major connurbations.

As householders move further into the peace, space and relative tranquility of the countryside, the properties of the inner suburbs they leave behind are bought up by landlords and converted into flats, which are typically badly maintained. The tone of the neighbourhood goes down, and more people move out.

Chief executive of the Chartered Institute of Housing, David Butler, said: "Unless more can be done to redress the imablance in regional economies, social housing landlords will continue to struggle with the problem of low demand in the north, while the pressure for new housing development in the south continues."