TAX the banks in your Budget, Rachel Reeves was told by campaigners today as pressure mounts on the Chancellor ahead of her make-or-break statement next month.

Protesters rallied in Westminster to demand that Ms Reeves seek to raise money by taxing the huge windfall profits made by the big banks.

The call came as fears mounted that downgraded productivity forecasts from the now-omnipotent Office for Budget Responsibility (OBR) would further widen the budgetary gap the Chancellor is seeking to close.

With the OBR set to slash productivity estimates by 0.3 per cent, this could leave Ms Reeves scrambling to find up to £20 billion to assuage City fears that government debt levels might spiral out of control.

Demonstrators argued that a windfall tax on the big four banks’ profits, in line with the rate imposed in Spain, could raise £14bn for the Treasury.

Protest organiser Hannah Dewhirst of Positive Money said: “The Chancellor just told us that those with the broadest shoulders should pay their fair share of tax. 

“Who has broader shoulders than the banks, which are reaping record profits without lifting a finger?”

Jake Atkinson of Tax Justice UK said: “One third of all children in the UK are living in poverty whilst big banks profiteer at the expense of the public.

“The upcoming Budget must raise living standards, not the champagne glasses of the banker bosses. A windfall tax on the retail operations of the big banks could raise billions to invest in communities across the country.”

And Nuri Syed Corser of War on Want said: “Our economic system is rigged: working people are struggling to get by and public services are crumbling, while banks, billionaires and the super-rich are dodging taxes and raking in cash.”

Ms Reeves was sticking to her new line that the problems were all down to Brexit.  

She blamed leaving the European Union for stubborn inflation — unchanged at 3.8 per cent — because of adding to the cost of trade.

She is now preparing for tax rises at a time when support for Labour is already collapsing.  

A YouGov poll puts its vote share at 17 per cent, a record low.

The survey put Reform in the lead with 27 per cent, the Tories also on 17, the Greens just a point behind Labour on 16 and the Liberal Democrats on 15 per cent, a picture of a deeply fragmented electorate.