That plan was itself a response to a previous successful legal challenge.

ClientEarth said that Energy Secretary Claire Coutinho is now “expected to have to draw up a new climate strategy within 12 months,” adding: “We’ll be watching.”

Prime Minister Rishi Sunak, speaking to Sky News, said he had not yet seen the judgment but added: “I’m proud of our track record, we’ve decarbonized faster than any other major economy around the world … But last year I set out a more pragmatic approach to get to net zero. Of course we believe in it, I want to get there, but we’re going to do that in a way that doesn’t saddle families with bills that we don’t need to.”

A Department for Energy Security and Net Zero spokesperson said the case had been “largely about process” and that the judgment contained “no criticism of the detailed plans we have in place.”

“We do not believe a court case about process represents the best way of driving progress towards our shared goal of reaching net zero,” the spokesperson added.

But ClientEarth lawyer Sam Hunter Jones said the courts “have now told the U.K. government, not once but twice, that its climate strategy is not fit for purpose.”