There is not enough evidence of policies in place that would actually reduce greenhouse gas emissions, the court said.

Energy Secretary Claire Coutinho must now prepare a revised plan within 12 months. The new plan must ensure that the UK achieves its carbon budgets as well as its pledge to cut emissions by more than two-thirds by 2030.

Environmental charities Friends of the Earth and ClientEarth, along with the Good Law Project, brought a legal case against the Department for Energy Security and Net Zero (DESNZ) over its decision to approve the carbon budget delivery plan last March.

Mr Justice Sheldon has now upheld four of the five grounds of their legal challenge, saying that the decision made by former energy secretary Grant Shapps was “simply not justified by the evidence”.

He said: “If, as I have found, the secretary of state did make his decision on the assumption that each of the proposals and policies would be delivered in full, then the secretary of state’s decision was taken on the basis of a mistaken understanding of the true factual position.”

A DESNZ spokesperson said: “The UK can be hugely proud of its record on climate change. Not only are we the first major economy to reach halfway to net zero, we have also set out more detail than any other G20 country on how we will reach our ambitious carbon budgets.

“The claims in this case were largely about process and the judgment contains 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.”