10 per cent fall in new developments in towns and cities raising fears about countryside The volume of formerly brownfield land which has been switched to residential use also declined from 69 per cent to 62 per cent. Ingrid Samuel, Historic Environment Director at the National Trust, said: "These figures show a worrying decline in the proportion of development taking place on previously developed land. The Government has said it wants to encourage the re-use of brownfield sites, but there is growing evidence that this is not happening in practice. Ministers should take action to ensure that they deliver on their commitments in this area. A National Trust spokesman added: "'We aren't calling for 100 per cent development on brownfield. Some greenfield development in line with local plans will be necessary to meet housing need. But If this trend continues we could see the unnecessary loss of green space. The figures are adjusted to include development in residential gardens, which makes it possible to compare the figures like-for-like with those issued before 2010. They date from before the Government introduced its new National Planning Policy Framework, which was fought by Telegraph readers through its Hands Off Our Land campaign. The framework was highly controversial because it introduced a new bias into planning rules in favour of "sustainable development." Earlier this week the National Trust warned ministers were presiding over a "steady erosion" of the green belt, with more than half of councils planning to build on protected countryside land despite other sites being available. The trust claimed half of the councils in England with green belt land are preparing to allocate some of it for development ahead of brownfield sites. It said that 51 per cent of councils it surveyed with green belts are now "likely" or "very likely" to allocate the land for development. A spokesman for the Communities department said: "These figures have changed since we've given councils new powers to stop garden grabbing and removed gardens from the definition of brownfield land. This is part of a wider package of reforms to stop unwanted garden grabbing. This Government is committed to building the homes our country desperately needs after house building fell to its lowest level since the 1920's under Labour. We are working hard to make use of every inch of brownfield land and today's official figures support that showing green belt development is at its lowest level on record; four times lower than in 1990. The green belt has a valuable role in protecting against urban sprawl and provides a green lung round our towns and cities. This Government has worked hard to safeguard national green belt protection by abolishing Labour's regional strategies which threatened to rip up the green belt, and introduced a new protection for valuable green spaces.