Brexit: MPs 'far more likely to reject deal' if denied chance to amend it, ex-Cabinet minister warns

MPs are far more likely to reject any Brexit deal if they are denied the chance to amend it in a proper “meaningful vote”, Theresa May has been warned.

A controversial move to only allow the Commons to accept or reject an agreement with the EU – preventing any amendments – will backfire by increasing opposition, Tory rebel Dominic Grieve predicted.

“If the government tries to pursue the route they are opting for, it is far more likely that the deal is likely to be rejected,” the former attorney general told an inquiry by MPs.

“You are confronted with an all-or-nothing choice – and you will not be able to go on and talk about anything else until you have rejected the deal.”

Mr Grieve – whose revolt, last December, won the “meaningful vote” – called for the debate to last 4 or 5 days, to let every MP “have their say”.

And he warned they would be “much more hostile” if they were denied the chance to make amendments until after “the guillotine has fallen” and the deal approved.

“To go back on this, or to try to avoid it, would be wrong – and it would be a big mistake,” he said.

The comments come after Dominic Raab, the Brexit secretary, was accused of breaking an earlier pledge, in a letter sent to the Commons procedure committee last week.

MPs had been told they would be able to bring forward an amendment requiring a Final Say referendum on the outcome of the talks, or perhaps to keep the UK in the EU single market or customs union.

But, in the letter, Mr Raab warned amendments would only be taken after a decisive vote on the main motion and, if the motion was defeated, might only be considered “points of view”.

The letter said: “Amendments – even those which may not intend to affect approval – may actually result in the government being unable to ratify the withdrawal agreement.

“It is important, however, to recognise the need ultimately for the House to consider the question that is in reality before the UK – whether or not to accept the deal that the government has negotiated with the EU.”

The prime minister already faces a daunting task to win parliamentary approval for her deal – even if she can unlock the talks, which remain deadlocked over the Irish border “backstop”.

Labour has vowed to vote against, unless six strict tests are met, and her strategy has triggered Tory protests over both the backstop and the Chequers plan for future trading rules with the EU.

Fifty Conservative MPs have joined the “StandUp4Brexit” campaign, demanding the hard Brexit first promised by Ms May, instead of her attempt to abide by the EU “rule book” on goods.

The procedure committee has launched an inquiry into the arrangements for the vote, which is unlikely to take place until nearly Christmas – or even next year.

Mr Grieve suggested, as a compromise, that MPs could vote on motions to make clear the Commons’ view on aspects of Brexit, without those being binding on the main motion.