A 'free for all' could be created for developers around Norwich because of a High Court ruling that a blueprint for where thousands of homes should be built is unlawful, council leaders have warned.

A huge question mark has been placed over the future of a strategy for where 37,000 homes should be built in Norwich, Broadland and South Norfolk after a campaigner's legal challenge was upheld by one of the country's top judges.

The document at the centre of the legal fight, the joint core strategy (JCS) is meant to serve as a blueprint for where development should happen over the next 15 years.

But Mr Justice Ouseley said the document had failed to explain what alternatives had been explored to plans for 10,000 homes to the north-east of Norwich, including at Rackheath.

He will decide next Wednesday what to do about the flaw in the strategy, which was drawn up by the Greater Norwich Development Partnership - made up of Norwich, South Norfolk and Broadland councils.

But the partnership's chairman said, if the strategy is delayed or sent back to the drawing board, it will be harder for authorities to stop speculative planning applications.

Andrew Proctor, who is also leader of Broadland District Council, warned a delay could lead to developers taking advantage of the vacuum.

He said: 'If the Joint Core Strategy is held up, it will be harder for us to challenge or prevent speculative development, and a free-for-all is in no-one's interests.

'The national housing shortage will not go away, and we are convinced that building communities that are high in quality and low in carbon will enhance the area for generations to come.'

'The judge has made it clear he is still to be persuaded on what final action to take, and we are working hard to address the issue at a second hearing to be held shortly when we will be making further submissions.

'We remain convinced that the Joint Core Strategy is needed not least because it is important to manage all forms of development in a planned way that takes account of the needs of those who will live, work in, and visit the area.'

The judicial review had been sought by Salhouse campaigner Stephen Heard, from Snub (Stop Norwich Urbanisation) on two points.

One was that alternatives to the plan for growth to the north-east of Norwich were not properly explored or explained.

The second was that the Northern Distributor Road (NDR) – a 'fundamental' part of the plan – or alternatives to it had not been environmentally assessed.

At one point during the two-day judicial review in December, Mr Justice Ouseley had likened the council's case to 'wading through treacle' and asked if the options had 'sprung fully formed from the brow of Zeus'.

And the judge yesterday ruled the document had not complied with legal directives. with the councils failing to properly explain how they had considered potential alternatives to the housing strategy mapped out in the strategy.

The judge said: 'It is part of the purpose of this process to test whether what may start out as preferred should still end up as preferred after a fair and public analysis of what the authority regards as reasonable alternatives.

'I conclude that, for all the effort put into the preparation of the JCS, consultation and its strategic environment assessment, the need for outline reasons for the selection of the alternatives dealt with at the various stages has not been addressed.'

He said that this constituted a 'breach on express terms' of a European Directive on the assessment of environmental effects.

He did not find any issue with the second point over the NDR, which, subsequently to the judicial review, has been awarded government funding.

The campaigners who launched the legal challenge said, at next Wednesday's hearing, they would be pushing for the judge to quash the strategy.

Mr Heard said: 'Whist we are pleased that the judge upheld our legal challenge on our first point we should never have had to be placed in a situation whereby a group of local residents had to put their lives on hold for a number of years to fight this through the courts.

'The GNDP and its member councils knew that here was a risk that the strategy was legally unsound as far back as 2008 yet they chose to ignore advice from a leading planning barrister that this was the case.'

He said the partnership had also ignored local parish councils who had made the case against the growth to the north east of Norwich.

He added: 'We also pointed out the flaws in their public consultations and the convoluted manner in which they were conducted, once again highlighted by the judge, and the difficulty that local residents had in finding the relevant documentation.'

Mr Heard dismissed the tag of SNUB as NIMBYs (Not In My Backyard) or a pressure group and stressed: 'We are none of these and have repeatedly stated that we recognise the need for additional houses but not in the manner represented in what is now an unlawful strategy.

'We will now take further legal advice on the next steps, which could include the quashing of the JCS. The campaign continues until the GNDP and the four local authorities see sense and present suitable alternatives for the public to have a view on.'

Mr Heard said next Wednesday's hearing will also see the judge decide what costs should be paid and appealed for anyone who wants to donate to email snub@orangehome.co.uk

It is understood that, at next week's hearing, the judge could decide to quash all or part of the strategy, request that further information is provided or could yet allow it to remain adopted despite the flaws.

But Nich Starling, Liberal Democrat and opposition leader on Broadland District Council said: 'Local people will rightly want to know how the council could have made such a major error on such an important issue.

'The Conservatives pushed this issue at Broadland and used their large majority on the council to waive aside and ignore any opposition.

'The Lib Dem group on Broadland has been proved right in its opposition to the strategy and we will ask the Conservatives to explain how much this flawed strategy has cost local taxpayers.'

David Merrick, head of development at Norwich-based estate agents and property consultants Savills, agreed with Mr Proctor that the lack of a joint core strategy would make it harder for councils to say no to developers.

He said: 'If there's not a joint core strategy which one can feel comfortable with, then it is going to be more difficult for local authorities to organised the release of land in the way they would look to. 'That will lead to a number of planning applications being made on a speculative basis. There will be developers saying 'there's nothing to base development on, so we will go for a hundred houses here or there.''

Mr Merrick also said a delay to the strategy would call into question the new Community Infrastructure Levy - a charge councils are planning to impose on future development, which is meant to pay for new roads, schools and open spaces.