It was first proposed around London by the Greater London Regional Planning Committee in 1935. The Town and Country Planning Act 1947 then allowed local authorities to include green belt proposals in their development plans. In 1955, Minister of Housing Duncan Sandys encouraged local authorities around the country to consider protecting land around their towns and cities by the formal designation of clearly-defined green belts.
The Government sets out its policies and principles towards the green belts defined by local authorities in England and Wales in Planning Policy Guidance Note 2: Green Belts
Local Councils are strongly urged to follow PPG2's detailed advice when considering whether to permit additional development in the green belt, or to assent to new uses being made of existing premises. In the green belt there is a general presumption against inappropriate development, unless very special circumstances can be demonstrated to show that the benefits of the development will outweigh the harm caused to the green belt. PPG2 also sets out a number of examples of what would constitute appropriate or inappropriate development in the green belt.
According to PPG2, there are five stated purposes of including land within the green belt:
Once an area of land has been defined as green belt, opportunities and benefits include:
By 2003, fourteen distinct green belts collectively restrict about 13 percent of England. In order of decreasing size these are as follows:
| Area (km²) | Cities |
|---|---|
| 5,133 | London (The Metropolitan Green Belt) |
| 2,578 | North West (Merseyside and Greater Manchester) |
| 2,556 | South Yorkshire and West Yorkshire |
| 2,315 | West Midlands |
| 825 | South west Hampshire and South east Dorset (Bournemouth/Poole, New Forest) |
| 688 | Avon (Bristol and Bath) |
| 663 | Tyne and Wear |
| 618 | Nottingham and Derby |
| 441 | Stoke-on-Trent |
| 350 | Oxford |
| 267 | Cambridge |
| 262 | York |
| 70 | Gloucester and Cheltenham |
| 7 | Burton upon Trent and Swadlincote |
| 16,766 Total |
Implementation of the notion dated from Herbert Morrison's 1934 leadership of the London County Council. It was first formally proposed by the Greater London Regional Planning Committee in 1935, "to provide a reserve supply of public open spaces and of recreational areas and to establish a green belt or girdle of open space". It was again included in an advisory Greater London Plan prepared by Patrick Abercrombie in 1944. However, it was some 14 years before the elected local authorities responsible for the area around London had all defined the area on scaled maps with some precision.
New provisions for compensation in the 1947 Town and Country Planning Act allowed local authorities around the country to incorporate green belt proposals in their first development plans. The codification of Green Belt policy and its extension to areas other than London came with the historic Circular 42/55 inviting local planning authorities to consider the establishment of Green Belts.
As the outward growth of London was seen to be firmly repressed, residents owning properties further from the built-up area also campaigned for this policy of urban restraint, partly to safeguard their own investments but often invoking an idealised scenic/rustic argument which laid the blame for most social ills upon urban influences. In mid-1971, for example, the government decided to extend the Metropolitan Green Belt northwards to include almost all of Hertfordshire. The Metropolitan Green Belt now covers parts of 68 different Districts or Boroughs.
The Town and Country Planning Association, an organisation heavily involved in initiating the concept several decades previously, published a policy statement in 2002 which proposed a more flexible policy which would allow the introduction of green wedge and strategic gap policies rather than green belts, and so permit the expansion of some urban areas. Similarly, in October 2007, Sir Martin Doughty, Chair of Natural England, argued for a review of green belts, saying: "The time has come for a greener green belt. We need a 21st century solution to England's housing needs which puts in place a network of green wedges, gaps and corridors, linking the natural environment and people.".
Lewis Abbott has identified greenbelt barriers to urban expansion as one of several major protectionist political-economic barriers to housebuilding with negative effects on the supply, cost/prices, and quality of new homes.(The others include new housing development taxes and quasi-taxes; political discrimination against particular classes of new housing supplier, household consumer, and housing product; and controls on housing technical-product development – in particular, the blocking of innovative low-cost housebuilding using new materials and production technologies). Abbott argues that the greenbelts actually defeat their own stated objective of saving the countryside and open spaces. By preventing existing towns and cities from extending normally and organically, they result in more land-extensive housing developments further out – i.e., the establishment beyond the greenbelts of new communities with lower building densities, their own built infrastructure and other facilities, and greater dependence on cars and commuting, etc. Meanwhile, valuable urban green space and brownfield sites best suited to industry and commerce are lost in existing conurbations as more and more new housing is crammed into them.
Other radical commentators such as James Heartfield and Alan Evans have called for outright abolition of green belts, principally on the grounds that by inhibiting the free use of land they restrict home ownership.
However, in England the concept of "green belt" has become entrenched as a fundamental part of government policy, and the possibility of reviewing boundaries is often viewed with considerable hostility by local communities and their elected representatives.

