LABOUR’S “obsession with fiscal responsibility” lost the party crucial support in the run-up to the general election, the leader of the Fire Brigades Union (FBU) said yesterday.

In an impassioned address to his union’s annual conference, general secretary Matt Wrack warned delegates to “build, campaign, organise and fight back” in the struggle of their lifetime.

Mr Wrack said unions and activists should be sceptical of calls from right-wing Labour figures for the party to move towards the centre.

“Ed Miliband gained the most ground when he made radical commitments, when he challenged Murdoch, when he challenged the energy companies,” he told the audience.

“The idea that what needs to happen is for Labour to dump those and move to the right is totally wrong.”

He said that the blame for the party’s wipeout in Scotland was entirely with Labour’s right wing.

“The idea that Labour would stand with Tories on platforms (during the indepdence referendum) was a disaster,” he said.

The FBU disaffiliated from Labour in 2004 following a heated industrial dispute with Tony Blair’s government over pay.

But relations between the union and the party have improved over the past year, with former Labour leader Ed Miliband whipping MPs to oppose recent attacks on firefighters’ pensions.

“We do have to acknowledge the movement that came from Labour,” Mr Wrack said, adding that it was largely a result of the efforts of union members.

“What we didn’t get was a clear commitment that an incoming Labour government would roll back the changes.”