LABOUR leader Sir Keir Starmer would be making a fatal error in ignoring the demands of grassroots party members, former shadow cabinet ministers warned today.

MPs Jon Trickett and Ian Lavery and ex-MP Laura Smith, who were all in former Labour leader Jeremy Corbyn’s top team, said that Sir Keir was wrong to argue against corporation-tax increases ahead of Wednesday’s Budget.

In a report published by the No Holding Back campaign, the trio note that “even a Tory Chancellor wants to see increases in corporation tax,” with Rishi Sunak rumoured to be considering the move.

“We must remember that corporation tax is a tax on big-business profits — not families,” they argue in the report, which is based on the views of a new activists’ assembly on Labour policy.

“Having spoken to many members of the labour movement over the last year, it is becoming clearer that the party is becoming more disconnected from its movement and values,” the report warns.

It notes widespread concern that the Labour leadership is going to make the “same mistake as it did in 2010, by accepting austerity as a core policy principle.”

Such a move would be in “opposition to the feeling in the wider country that austerity failed Britain, leading it to be ill-equipped and unprepared for the pandemic,” it says.

Its foreword, written by Mr Trickett, also notes that discontent on the Labour left has been fuelled by the treatment of Mr Corbyn, who was stripped of the party whip over his response to the equalities watchdog’s report on anti-semitism.

The report’s release came after former shadow justice secretary Richard Burgon urged Labour to be bolder in offering an alternative to the failed Tory policies of the last decade.

During a Labour Assembly Against Austerity event on Monday night, he said: “Labour’s leadership has said this must be a 1945 moment — a fork in the road.

“It is our job to lead the debate on what that new economy looks like.

“The crisis is now, and so the Labour Party needs to have answers now. We can’t just sidestep big debates.

“The tax debacle of the past few days shows that if we continue to do so, then our party will be outflanked by the phoney Tory rhetoric of levelling up.

“It will be our communities that pay the price.”

The Labour Party was contacted for comment.

The No Holding Back activists’ assembly report on the Budget can be accessed at: bit.ly/NHBReport.