A proposal to build around 3.5 million new homes in England by doubling the size of 40 cities over the next 30 years has won the Wolfson Economics Prize 2014.

Town planner David Rudlin won the £250,000 prize with his vision of a new generation of garden cities, which would each have about 86,000 new homes for around 150,000 people. The plan would mean building into the green belt surrounding cities such as York, Stafford, Cheltenham, Northampton, Oxford, Cambridge, Exeter, Harrogate, Lincoln, Durham, Stratford-on-Avon, Norwich, Salisbury and Canterbury.

Mr Rudlin, who manages the urban design consultancy URBED said that extending towns into the green belt is the best way to achieve growth while still protecting the countryside in surrounding villages from unwanted expansion. But he suggested that towns and cities should be allowed to bid for garden city status instead of having expansion forced onto them.

The model is based on town extensions in Germany, Scandinavia and Holland where the expanded areas are served by buses or trams, and include green neighbourhoods with schools, shops and amenities within walking distance. The influx of new residents should revive existing town centres, according to the proposal.

Around 20% of the new homes , set in circle-shaped developments, would be affordable housing - and green space would be preserved by building plenty of parks and gardens. Some sites would also be handed over to people wanting to build their own homes.

John McLarty from Strutt & Parker’s Planning department said: “This year’s Wolfson Prize winner David Rudlin has again put the spotlight on the challenging issue of housing growth in the green belt. There is no doubt as we look to a sustainable future of our larger towns and cities the green belt will have to be considered for growth. As David Rudlin’s winning entry has established, our key cities have excellent transportation links and access to wider facilities which means the green belt debate needs to identify ‘real opportunities’ where we can realign boundaries and create garden cities within the countryside.

He continues: “The economic case is clear but this must also be balanced by environmental stewardship and enhancement as part of a comprehensive review.”

The competition judges praised Mr Rudlin’s entry for its “personal and human-scale” vision which was transferable around the UK. It also includes a 6-point “social contract” to address objections, aimed at minimising environmental damage by avoiding flood plains, concealing housing within the landscape and providing new community facilities – including renewable energy schemes.

The £50,000  runner-up prize was won by homeless charity Shelter, for its plans to build a garden city housing 48,000 people at Stoke Harbour on the Hoo peninsula between Medway, Kent and the Thames river.

The competition attracted 279 entries, and the organisers said that the different entries have provided “valuable ideas about how best to deliver a garden city which is visionary, economically viable and popular.”