Jacob Rees-Mogg and Boris Johnson join FOBT rebellion

Theresa May’s government faces becoming the first to suffer a defeat on its own budget bill in 40 years after Tory MPs including Jacob Rees-Mogg, Boris Johnson and David Davis joined a rebellion over fixed-odds betting terminals (FOBTs).

More than 70 MPs from both sides of the House of Commons have signed two amendments that, if passed, would effectively force the government to bring forward the timing of the planned cut in FOBT maximum stakes to April 2019.

The sports minister Tracey Crouch quit the government this month after the chancellor, Philip Hammond, revealed in the budget that the policy would not take effect until October 2019.

She has joined dozens of party colleagues in putting her name to amendments that could force the Treasury to revert to the earlier date, understood to have been included in an early draft of the budget.

The rebels also include Johnny Mercer, Priti Patel, Justine Greening, Zac Goldsmith and Treasury committee chair Nicky Morgan while MPs from Labour, the Liberal Democrats, DUP, SNP and Plaid Cymru have also signed.

The shadow chancellor, John McDonnell, said on Monday that Labour would support the amendment, after the Guardian revealed that a “discredited” report commissioned by bookmakers had influenced the Treasury’s decision on the timing of FOBT stake reduction.

Support from Labour for the amendment, coupled with dozens of signatures from all sides of the House of Commons, mean it would be all but certain to pass.

No government has been defeated on its own finance bill since Jim Callaghan’s minority administration was voted down on income tax rates in 1978.

The two amendments have been laid by the Labour MP Carolyn Harris, the former Tory leader Iain Duncan Smith and the SNP’s Ronnie Cowan.

Together, they have the combined effect of forcing the government to bring forward the date of the cut to maximum stakes on fixed-odds betting terminals (FOBTs) from October 2019 to April 2019.

They say that an increase in taxes on online casinos – intended to make up for lost revenue from the FOBT cut – cannot happen at all unless the latter policy is brought forward.

The government could avoid defeat on the amendment by overturning its own decision before the vote is held.