Rebels say they could back fresh amendment if May does not stick by assurances on EU withdrawal bill

Theresa May must stand by assurances she gave to Conservative MPs to halt their rebellion over the EU withdrawal bill or the Lords may bring a new amendment for rebels to back, leading members of the group have said.

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The former education secretary Nicky Morgan, one of more than a dozen MPs who met the prime minister in the final minutes before the House of Commons vote, which threatened a government defeat, said May had given them personal assurances a compromise amendment would be brought by the government.

If that compromise did not emerge, Morgan said rebels could work with the Lords to ensure the changes took place. “I think it would be fairly certain that one of the members of the House of Lords would find a way to put down Dominic [Grieve]’s original wording, that couldn’t be voted on yesterday. So we are partway through discussions and there is more to come,” she said.

After the rebellion was averted on Tuesday night, several Brexit-backing Conservative MPs and ministers suggested May had not compromised and had only agreed to further talks on backing Tory rebel Dominic Grieve’s amendment to give parliament a meaningful say should a “no deal” Brexit loom.

Pro-Europe MPs said May had assured them the government would accept two parts of the former attorney general’s amendment – a vote on the final deal and a statement from ministers to seek approval from parliament for the next steps if no deal be reached by November.

The MPs said May had also agreed to further talk on the third part of Grieve’s amendment, “part C”, which would allow MPs to direct the government if no deal is reached by February next year.

The solicitor general, Robert Buckland, who intervened from the dispatch box to offer the last-minute concessions that led to the would-be rebels’ meeting with the prime minister, suggested that there would be no further compromise on part C, contrary to what MPs say they were told.

“I have a problem both constitutionally and politically with a direction given by parliament, which is the end part of Dominic Grieve’s amendment,” he told BBC Radio 4’s Today programme.

Buckland intimated the government had not fully committed to any part of Grieve’s amendment. “I’m looking forward to the discussions and it’s right to say that I’ll be looking at potential drafts of what an amendment could say,” he said.

“There’s a reasonable expectation that something will emerge, but I need to work on that and more importantly work with colleagues to come up with something.”

Morgan, who met the prime minister along with Grieve and a dozen more MPs including Sarah Wollaston, Antoinette Sandbach, George Freeman and Justine Greening, said there had been specific assurances as discussions came “down to the wire”.

“The prime minister conceded she understood points a and b of the Dominic Grieve amendment and there will be further discussions on c, with a view on bringing the amendment in the House of Lords, so that will be discussed further,” she said.

“The gap is: what happens if there is no deal? How does parliament have a say in those circumstances? I think that is very important that our sovereign parliament gets to express its opinion.”

Morgan admitted there was a part of the Grieve amendment that “does go further” than the prime minister was prepared to accept but said the would-be rebels had not been played.

“I don’t think that’s right,” she said. “Part of the reason we had the meeting with the prime minister and the chief whip is we have had undertakings given at the dispatch box which have not been fulfilled ... it was the prime minister’s personal assurance that was important to us.”

A series of further votes on the EU withdrawal bill will take place on Wednesday, but no defeats are expected after ministers agreed a compromise wording over post-Brexit plans for a “customs arrangement”.

Labour MPs are expected to rebel against their party whip in significant numbers to vote in favour of a Lords amendment to keep the UK in a Norway-style trading arrangement post-Brexit. The official Labour position will be to abstain.