The study by the London Society says the green belt’s "preservation myth" needs to be dispelled with the recognition that new development will be required on some of it.
The society first called for a green belt to be established around the capital in a pioneering development plan in 1919 that, it said, laid the basis for the first green belt policies of the 1940s.
The report, authored by Jonathan Manns, associate director of planning at consultancy Colliers International, points out that the city’s population is expected to reach over 10 million by 2030 – requiring an extra one million homes for London.
With housebuilding levels at their "lowest for a generation", the paper calls for a "joined-up approach to growth" involving discussions about development in the green belt, a challenge that requires "strong, central leadership".
The development of new infrastructure, such as expanded London airports and Crossrail, "create a real opportunity for this growth to be plan-led and sustainable".
Building one million new homes, even at a low density of 40 dwellings per hectare, would require just 4.8 per cent of London’s current 516,000-hectare green belt.
New housing in the green belt could involve "the release of parcels on the city fringe, expansion of existing satellite towns or development of new settlements elsewhere".
Elsewhere, the document suggests that "green wedges" or urban extensions may be appropriate, adding that it was "imperative" that such ideas were immediately considered.
It is time to "to move away from the simplistic and naïve idea that that countryside is a sacrosanct patchwork of medieval hedgerows", the document argues.
Green Sprawl: Our Current Affection for a Preservation Myth can be downloaded here.