The new towns in the United Kingdom were planned under the powers of the New Towns Act 1946 and later acts to relocate populations in poor or bombed-out housing following the Second World War. They were developed in three waves. Later developments included the expanded towns: existing towns which were substantially expanded to accommodate what was called the "overspill" population from densely populated areas of deprivation.
Designated new towns were removed from local authority control and placed under the supervision of a development corporation. These corporations were later disbanded and their assets split between local authorities and, in England, the Commission for New Towns (later English Partnerships).
- Letchworth, Hertfordshire (founded in 1903 through the Garden city movement).
- Welwyn Garden City, Hertfordshire (founded in 1920 through the Garden city movement).
- Out-county London County Council housing developments, of which Becontree, Dagenham, was the largest. It was built in the 1920s and 1930s.
- Seacroft in Leeds was built from 1934 when Leeds City Council bought 1,000 acres (4.0 km2) for municipal housing, and after World War II the majority of houses and blocks of flats were built. The council had planned for Seacroft to be a "satellite town within the city boundary" 
- Wythenshawe was built on former rural land in the north of Cheshire between the 1920s and early 1970s to rehouse families from the inner city slums of Manchester as an overspill estate. Other Manchester overspill estates include Hattersley (mostly built during the 1960s), Gamesley, and Haughton Green.
- Castlemilk, Drumchapel, Easterhouse and Pollok in Glasgow.
- Castle Vale in Birmingham, which was built in the 1960s in the extreme north-east of the city.
The first wave was intended to help alleviate the housing shortages following the Second World War, beyond the green belt around London. A couple of sites in County Durham were also designated. These designations were made under the New Towns Act 1946.
- Stevenage, Hertfordshire (designated 11 November 1946)
- Crawley, Sussex (designated 9 January 1947)
- Hemel Hempstead, Hertfordshire (designated 4 February 1947)
- Harlow, Essex (designated 25 March 1947)
- Newton Aycliffe, County Durham (designated 19 April 1947 as Aycliffe New Town)
- Peterlee, County Durham (designated 10 March 1948, as Easington New Town)
- Welwyn Garden City and Hatfield, Hertfordshire (both designated 20 May 1948)
- Basildon, Essex (designated 4 January 1949)
- Bracknell, Berkshire (designated 17 June 1949)
- Corby, Northamptonshire (designated 1 April 1950)
The second wave (1961–64) was likewise initiated to alleviate housing shortfalls. Two of the locations below (Redditch and Dawley New Town—later renamed Telford) are situated near the West Midlands conurbation; another two (Runcorn and Skelmersdale) are near Merseyside and were intended as overspill for the city of Liverpool.
- Skelmersdale, Lancashire (designated 9 October 1961)
- Dawley New Town, Shropshire (designated 16 January 1963)
- Redditch, Worcestershire (designated 10 April 1964)
- Runcorn, Cheshire (designated 10 April 1964)
- Washington, Tyne and Wear (designated 24 July 1964)
The third and last wave of new towns (1967–70) allowed for additional growth chiefly further north from the previous London new towns, with a few developments between Liverpool and Manchester, namely "Central Lancashire" and Warrington. Dawley New Town was redesignated as Telford New Town, with a much larger area, as overspill for Birmingham and nearby towns including Wolverhampton. About halfway between Birmingham and London was the new town of Milton Keynes (which took its name from a village in the area, but also swallowed up the existing towns of Bletchley, Wolverton and Stony Stratford), while the existing town of Northampton was expanded. In East Anglia, the city of Peterborough was designated as a new town to accommodate overspill from London.
- Milton Keynes, Buckinghamshire (designated 23 January 1967)
- Peterborough, Cambridgeshire (designated 21 July 1967)
- Northampton, Northamptonshire (designated 14 February 1968)
- Warrington, Cheshire (designated 26 April 1968)
- Telford, Shropshire (designated 29 November 1968)
- Central Lancashire, Lancashire (designated 26 March 1970)
Other 'overspill' developments
During the same period as the new town scheme, several other towns underwent local authority led expansion as 'overspills' to larger urban areas, but were not officially designated as new towns, among these were:
- Cramlington, Northumberland
- Daventry, Northamptonshire
- Killingworth, Tyne and Wear
- Tamworth, Staffordshire
Subsequent town expansion schemes
No new towns have been formally designated since 1970, but several new large scale developments have been founded:
- Cambourne, Cambridgeshire
- Bar Hill, Cambridgeshire
- South Woodham Ferrers, Essex
- Ebbsfleet, Kent
- Wixams, Bedfordshire
- Sherford, Devon
- Northstowe, Cambridgeshire (planned)
- Cranbrook, Devon
- Nansledan, Cornwall
- Welborne, Hampshire
Poundbury is an experimental new town or urban extension on the outskirts of Dorchester. The development is built on land owned by the Duchy of Cornwall. It is built according to the principles of Prince Charles, who is known for holding strong views challenging the post-war trends in town planning that were suburban in character.
On 13 May 2007, chancellor Gordon Brown, who became Prime Minister of the United Kingdom the following month, announced he would designate 10 new "eco-towns" to ease demand for low-cost housing. The towns, around 20,000 population each—at least 5,000 homes—are planned to be "carbon neutral" and will use locally generated sustainable-energy sources. Only one site was identified in the announcement: the former Oakington Barracks in Cambridgeshire—the already planned Northstowe development. Local councils will be invited to provide sites for the remaining four towns.
The Town and Country Planning Association is advising the government on the criteria and best practice in developing the eco-towns by producing a series of "worksheets" for developers.
Modern developments outside the scheme
Six new towns in Scotland were designated between 1947 and 1973, mostly for the overspill population of Glasgow.
- East Kilbride (designated 6 May 1947)
- Glenrothes (designated 30 June 1948)
- Cumbernauld (designated 9 December 1955, extended 19 March 1973)
- Livingston (designated 16 April 1962)
- Irvine (designated 9 November 1966, and encompassing existing settlement of Kilwinning)
- Stonehouse (designated 17 July 1973, never built)
Modern developments outside the scheme
- Ravenscraig (in progress)
- Chapelton of Elsick (in progress)
- Tweedbank, new village built in the 1970s on a greenfield site in the central Scottish Borders. (population 2,073)
- Erskine and Inchinnan, small new town developed in the 1970s and 1980s in Renfrewshire. (population 16,601)
- Dalgety Bay, small new town developed in the 1970s and 1980s in Fife. (population 10,777)
- An Camas Mòr: new settlement proposed in the Cairngorms National Park
- Blindwells: new settlement proposed adjacent to Tranent in East Lothian
- Calderwell: new settlement proposed adjacent to East Calder and Livingston in West Lothian
- Durieshill: new settlement proposed in Stirling Council area adjacent to Plean
- Forestmill: new settlement proposed in Clackmannanshire in close proximity to the Fife Council administrative boundary
- Oudenarde: new settlement proposed adjacent to the Bridge of Earn in Perthshire
- Owenstown: new settlement proposed in the South Lanarkshire area to the south of Lanark
- Shawfair: new settlement proposed in SE Edinburgh spanning the City of Edinburgh Council and Midlothian Council administrative boundaries
- Tornagrain: new settlement proposed to the south of Inverness Airport in the Highland Council area
The New Towns Act 1965 gave the Minister of Development of the Government of Northern Ireland the power to designate an area as a new town, and to appoint a development commission. An order could be made to transfer municipal functions of all or part of any existing local authorities to the commission, which took the additional title of urban district council, although unelected. This was done in the case of Craigavon.
The New Towns Amendment Act 1968 was passed to enable the establishment of the Londonderry Development Commission to replace the County Borough and rural district of Londonderry, and implement the Londonderry Area Plan. On 3 April 1969, the development commission took over the municipal functions of the two councils, the area becoming Londonderry Urban District.
- Craigavon (designated 26 July 1965)
- Antrim (designated 1966)
- Ballymena (designated 1967)
- Derry (designated 5 February 1969) 
In July 2002 the Select Committee on Transport, Local Government and the Regions assessed the effectiveness of the new towns and concluded that:
While many New Towns have been economically successful, most now are experiencing major problems. Their design is inappropriate to the 21st Century. Their infrastructure is ageing at the same rate and many have social and economic problems. Many are small local authorities which do not have the capacity to resolve their problems. Their attempts to manage the towns are complicated by the role played by English Partnerships which still has major landholdings and other outstanding interests.
The new towns are no longer new and many of the quickly built houses have reached the end of their design life. The masterplans dictated low density development with large amounts of open space, and housing segregated from jobs, shopping and business services. These created a car dependency and are now not considered sustainable. Low density developments are expensive to maintain. Roads and sewers are in need of expensive upgrades.
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- CBI Calls For 10 New Towns and Garden Cities
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- "Archived copy" (PDF). Archived from the original (PDF) on 2016-11-29. Retrieved 2016-11-29.CS1 maint: archived copy as title (link)
- Regions Nineteenth Report 2002, para.2.
- Regions Nineteenth Report 2002, para.13,14.
- "Select Committee on Transport, Local Government and the Regions Nineteenth Report". Select Committee on Transport, Local Government and the Regions. Archived from the original on 2016-03-03. Retrieved 31 January 2016.
licensed under Open Government Licence
- A commentary by the Government of Northern Ireland to accompany the Cameron Report incorporating an account of progress and a programme of action, CAIN web service, 1969