An estimated 10 million retirees will lose their winter fuel payments. This benefit will still be paid to those who receive pension credit or other means-tested benefits.

A pre-action letter sent to the government by Unite’s legal representative on October 29 argued that the government had not made a full assessment of how the decision would affect people.

The government announced in September that a comprehensive assessment had not been carried out but that a more limited “equality analysis” had been published.

The letter named Work and Pensions Secretary Liz Kendall as a proposed defendant. Although the union demanded a response by November 7, the government technically has 14 days until November 12 to respond.

The government was asked for comment.

The letter also said the government had a legal duty to refer the cut to the Social Security Advisory Committee and was required by law to gather further evidence about the impact of the cut, particularly on vulnerable and disabled people.

The letter said the issue was “urgent” due to the increasingly cold weather and the significant impact on people “who are at risk of disconnection and increasingly having to give up adequate heating and cut other essential expenses”.

“People don’t understand, and I don’t understand how the Labor government is taking fuel benefits away from millions of pensioners as winter approaches,” Graham added.

Prime Minister Keir Starmer has previously defended the “difficult” decision to cut universal benefit.

Sir Keir said the cut was necessary due to the country’s financial situation and accused previous governments of avoiding confronting issues such as the cost of winter fuel payments.

A couple in Scotland have been given permission to present their own legal bid against both the UK and Scottish governments over the cancellation of aid.