The Big Question: What is the Green Belt, and do we really need to preserve it?

Why is this important now?

In 2003, Tony Blair and Gordon Brown commissioned a senior economist, Kate Barker, to take a long, hard look at the supply of housing. Her report, published in 2004, warned that while demand was rising all the time, there was no matching increase in supply. In 2001, the number of new homes had fallen to the lowest level since the Second World War. In January, Kate Barker was commissioned to write a second report, on whether planning laws hinder house building. Almost every developer says they do. One of many complaints is that too much of the land is a no-go for developers because of the "green belt" that surrounds every major city. The Barker report will be published today.

So, what is the "Green Belt"?

Before and after the war, town planners became alarmed by the way big cities were spreading out. Lines of new houses stretched like ribbons along the main roads, until they reached what had once been a separate community, which was then swallowed by the city. Thus Bromley, in Kent, for example, vanished into Greater London. In August 1955, the housing minister, Duncan Sandys signed an order permitting local authorities to surround towns with "green-belt" land where all housing development was forbidden.

The idea rapidly caught on. In England alone there is now nearly 1.7 million hectares (6,480 square miles) of green belt. This is not the only part of the countryside where development is banned. There are, for example, 3,830 square miles of National Parks in England. There are also sites of outstanding natural beauty, special areas of conservation, and sites of scientific interest. Altogether, more than 55 per cent of England's land area is protected against developers.

Where can the builders build?

There is some land that is not designated as Green Belt, or protected in any other way, which is still undeveloped, but it has been acknowledged for years that there is not enough. Soon after Labour came to power, they set a target that by 2008 at the latest, 60 per cent of all new homes should be built on what are called 'brownfield' sites or land that has already been built on, but is not being used for its original purpose. The decline of heavy industry has left large tracts of empty land where there used to be factories.The Environment Agency has calculated that there is 66,000 hectares (255 square miles) of brownfield land available for redevelopment. - an area as large as the entire west Midlands conurbation.

With all that land, why do developers want more?

No one can accuse the developers of ignoring the government's plea to build on brownfield sites. They reached the target of 60 per cent of new homes being built on brown sites as early as 2000 - eight years ahead of the deadline set by government. As well as helping preserve the countryside, this had the added advantage that because the sites were already in urban areas, the new homes were generally close to facilities like roads, shops, and schools. But one obvious problem is that the largest areas of brownfield sites are in those parts of England where industries have been closing down, the very places from which people are moving out. The demand for housing is greatest in London and the south east, where disused industrial land is comparatively scarce.

Is anyone suggesting that the Green Belt be abolished?

No. There is an old, old battle between developers and people who do not want land near their homes to be built on, whichever government in power. It was a Conservative minister who coined the term "nimby-ism" for people who say that new houses are okay, but "not in my back yard". On the other side of the argument, people who fear having the view from their windows ruined accuse the government of wanting to "concrete over the countryside". But Kate Barker's 2004 report calculated that even if the Government chose to build an additional 120,000 houses every year for 10 years, all in the South-east, they would cover just 0.75 per cent of the region's total land area, or 1.92 per cent of developable land. Actually, building on that scale is not likely.

Barker will probably point out that not all the "Green Belt" is open countryside. Cambridge airport, for example, is in the Green Belt. If it closes, which it may do, there does not seem to be any compelling reason that the land could not be used for housing. In other words, she will call for a little local relaxation of green-belt rules.

Who gains, and who loses?

The losers, obviously, will be people whose bedroom windows overlook the countryside, who could have their view ruined by a new housing estate. And if genuinely beautiful sites, or sites of special interest, disappear under concrete, we all lose. The obvious gainers are the developers and landowners. There is a vast price difference between protected land and land suitable for development.

In July, Kate Barker reckoned that farmland was worth, on average, £10,000 per hectare, compared with £2.6m per hectare for housing land. It already happens that some landowners in the green belt deliberately leave their land looking as ugly as possible, in the hope that no one will object to it being developed. On the other hand, some brownfield sites are so contaminated by industrial use that the profit from improving the land is almost all soaked up by the cost of cleaning it up. Barker floated the idea of a windfall tax on landowners whose land benefited from a change in planning rules, but that idea will probably be dropped.

Why help make rich landowners and developers richer?

It should not be forgotten that there are a lot of people whose lives are now blighted by the housing shortage. Two groups are particularly affected. The people hardest hit by the rising price of owner-occupied homes are first-time buyers. In 1969, a first home cost an average of £4,111. That had gone up to £53,026 by the time Labour returned to power in 1997. Labour managed to keep inflation generally under control for eight years, yet by 2005, getting onto the housing ladder cost £142,615 on average. Possibly the worst affected are those on low incomes, who rely on some form of social housing, like council housing. In 1966, 142,000 new social rented homes were built. By 1994-95, that figure had fallen to 42,700. By 2002-03, it was down to 21,000, and last year, 18,000. The housing charity, Shelter, wants the Government to build an extra 20,000 "social" homes a year to cope with the shortage.

Should we build houses on protected land?

Yes...

* Designated Green Belt covers thousands of square miles, including some very unattractive areas

* Demand for homes is rising, but fewer and fewer are being built

* Even if the Government put 10,000 new homes a year on land that is currently protected, it would only take up a fraction of the total amount

No...

* Loosening the rules would offer a bonanza to big property developers and rich landowners

* Current policy protects small towns close to cities from being sucked into urban sprawl

* Climate change will worsen if the countryside disappears under concrete