A High Court judge has quashed permission for one of the world's largest offshore wind farms to be built off the east coast of England.
The Norfolk Vanguard Offshore Wind Farm was granted development consent in July by the Secretary of State for Business, Energy and Industrial Strategy (BEIS).
But Mr Justice Holgate overturned the decision following legal action from a man living near a planned cable route.
A Department for BEIS spokeswoman said it was "disappointed by the outcome".
"We will be considering the judgment carefully before deciding next steps," she added.
The legal challenge was brought by Raymond Pearce, who lives near Reepham in Norfolk, who had raised concerns about the effect the development would have on the landscape and the view.
He argued that ministers had not taken into account the "cumulative impacts" of the project, proposed by the energy company Vattenfall, and had given "inadequate" reasons for not doing so.
Trenches, into which cables would be laid from the wind farm to onshore substations, would pass within 80m (262ft) of Mr Pearce's house.
Mr Justice Holgate said the Vanguard development was closely related to a second wind farm project called Norfolk Boreas.
The judge heard that a substation site planned for both projects near Necton, about 40 miles (65km) from the coast, had attracted "substantial objections".
Ruling in Mr Pearce's favour, he said regulations had been breached as a result of a failure to evaluate available information about the "cumulative impacts of the Vanguard and Boreas substation development".
Speaking to BBC Look East after the ruling, Mr Pearce accepted it was not an "outright" victory, but added "it's a very good start though".
He said: "For the people of Norfolk who will be potentially adversely impacted by multiple cable corridors then it really is a very good start, that finally they have a voice and somebody is recognising these national infrastructure projects will have an impact on ordinary people's lives."
He said it was "absolutely fantastic we are progressing towards a zero-carbon economy", but that "the impact in just developing the onshore infrastructure will be devastating, not only on the climate... but on the local environment".
According to Vattenfall, whose application was granted development consent last year while Alok Sharma was business secretary, the proposed wind farm would provide enough electricity to power the equivalent of 1.95 million homes.
It said it was "a very disappointing outcome", but pointed out the decision "relates to the process for granting consent and is not about the merits of our world-class Norfolk Vanguard project".
Danielle Lane, Vattenfall's UK country manager, said the company had "fulfilled all the requirements placed on developers".
She added it was "vital that the government now acts to re-determine consent, with regard to the judge's ruling, as quickly as possible".