James Gorst's proposed Garden House scheme in north London is in tatters after a High Court judge ruled in favour of a group of opponents including Marco Goldschmied and Borat actor Sacha Baron Cohen.
Gorst won planning for his scheme in Hampstead in January 2006, but it was met with fierce opposition from the Heath and Hampstead Society, backed in part by former RIBA president Goldschmied and Ali G creator Baron Cohen.
The campaigners forced a High Court judicial review of the contentious plans, which were eventually thrown out by Mr Justice Sullivan on 3 April.
Gorst had proposed replacing an existing 1951 house, which is located on privately owned Metropolitan Open Land (MOL), with a new, one-off residential development.
Under Planning Permission Guidance 2, a house on privately owned MOL - which has the same protection as green-belt land - can only be replaced by a house which is not 'materially larger'.
Gorst's scheme, supported by Camden Council, was two to three times larger than the existing building, but Camden Council believed it had less visual impact than the original house, as most of the massing was to the rear.
Mr Justice Sullivan said that size alone was the criterion by which to interpret the words 'materially larger', and that should the proposals be granted it would see MOL 'suffer the death of a thousand cuts'.
He therefore ruled that the application be 'quashed'.
The news came as a massive blow to Gorst, who has been fighting for the scheme for more than two years.
He said: 'It's an outrage, we're all very disappointed. This ruling strips all local authorities of the responsibilities or powers to decide any development on its individual merits. It will have massive repercussions.
'Our scheme was mathematically larger but the volume of it was nowhere near the numbers they were claiming. Besides most of the extra volume was to the rear of the building, using up dark, dank, hidden space.'
Camden Council was ordered to pay the Heath and Hampstead Society £18,000 in legal costs including VAT.
The council said it would appeal the decision, although Mr Justice Sullivan said any appeal application would be 'utterly hopeless'.