A Cambridge University study has claimed millions of people are living in homes that are too small for them, and the poorest are being hardest hit, what the academics call 'rabbit hutch' Britain.

The academics at Cambridge should know. It is one of those towns, forty miles from Central London, that is booming as a result of London's suffocating 'green belt'. London house prices have been soaring, and people who work in the capital have been forced to find homes further and further away. They blame foreign property buyers, or even the government's Help to Buy schemes, for the surge in prices. But that is only part of the story. The fact is that London, like many other cities in the UK, is not building enough houses. To meet the demand, the UK would have to build around 260,000 houses each year. Last year, it built just 110,000. And, like the national debt, that deficit has been stoking up housing pressure for at least the last thirty years.

It is near-impossible to build houses to meet that demand hangover. The green belts, announced in the Town and County Planning Act of 1947 and introduced in the early 1950s, were supposed to be slim areas of woodland and farmland surrounding our cities. The idea was to stop 'urban sprawl' and to give city dwellers some nice countryside nearby that they could enjoy. The farmland, however, has become industrial farmland, more like the prairies of the MidWest rather than the bucolic idyll of Olde England, and quite inaccessible to the public. Meanwhile this so-called 'green' belt has been extended further and further as people living in it or near it campaign to stop development near them – which, if successful, means that their home rises in value because of the huge unfulfilled demand. So 73% of Surrey, near London, is now green belt, and the few houses their command huge premium values, as do those in the other Home Counties. In the cities themselves, space has become so valuable that homes have indeed become rabbit hutches.

As Paul Cheshire, Professor of Economic Geography at the London School of Economics (and a recent speaker at the Adam Smith Institute) points out, greenbelts are a form of discriminatory zoning. They deliver no real benefit to a poor child in Haringey, five miles away from the green belt. But they do deliver benefit to the stockbroker-belt residents, keeping the urban unwashed and their housing out of their backyard.

The Adam Smith Institute has suggested that 800,000 new homes could be built around the capital by shaving just half a mile off each boundary of the London green belt. Politically, of course, that is difficult. Every homeowner in London, and particularly those around the green belt, have an interest in keeping the supply restricted. Cheshire has another suggestion. Because of the green belt restrictions, if you can get planning permission on a piece of land, its value soars. Cheshire would simply say that when that premium reaches a certain level, it is obvious that the market is telling you something. And where the premium is highest, that is where we should release land for new building.