The pledge came as MPs rejected a last-ditch attempt to amend legislation at the centre of “power grab” claims before it leaves the Commons for the House of Lords.
Scottish Conservative MPs voiced their anger at ministers for failing to fix Clause 11 of the EU (Withdrawal) Bill in the Commons, but voted with the government against a Labour amendment, prompting accusations that they had “rolled over to protect their party”.
Labour’s amendment giving devolved assemblies unrestricted power to legislate in devolved areas was defeated by 297 votes to 321. The Withdrawal Bill, which as currently drafted reserves 111 powers in devolved areas at Westminster, now moves to the Lords.
In a veiled threat to ministers that they may not be able to rely on Scottish Conservative loyalty in future, Stirling MP Stephen Kerr said: “I want this to be heard: the government made a clear commitment to the house on the amendments to Clause 11 and I took those commitments at face value, and as a Conservative member, obviously I never want to get to the point where I can’t take commitments given to me by honourable and right honourable members on face value.
“Because I hope, frankly, that my honourable and right honourable friends can continue to trust commitments that I might make to them.”
Mr Kerr said the bill was leaving the Commons in an “unsatisfactory state”, and lamented the lost opportunity for amendments to have “pulled the rug from under [the SNP’s] squalid argument”.
“It would have shown them up as the creators of grievance rather than giving grievance a voice,” he said. “The government had control of the timetable. The deadlines were created by them, but they have let this chamber down by not delivering on what they promised.”
Mr Kerr added: “It sticks in my craw. It’s not really good enough, and as a member of the House of Commons I hang my head to think that we have somehow dropped the ball.”
The UK government has pledged to overhaul Clause 11 in the Lords once agreement is reached with the Scottish Government on how powers in some areas will shared between London and Edinburgh.
Cabinet Office minister David Lidington said devolved nations would end up with greater powers at the end of the Brexit process, and said the government would “shortly publish our analysis of the areas where frameworks will and will not be needed”.
The Scottish Government’s Brexit minister Michael Russell said it was pressing ahead with a “continuity bill” at the Scottish Parliament that would pose a direct challenge to Westminster’s constitutional sovereignty.
“Accepting this evening’s amendment would have been a clear commitment to correcting the bill,” Mr Russell said.
“As it stands, there is no prospect of the Scottish Government recommending to the Scottish Parliament that this bill should receive legislative consent.
“The Scottish Parliament’s cross-party constitution committee agreed that the Withdrawal Bill, as drafted, is ‘incompatible with the devolution settlement’. We therefore have no choice but to press ahead with legislation at Holyrood if that’s what it takes to defend devolution.”
Labour’s Lesley Laird, the Shadow Scotland secretary, claimed the episode revealed that Scottish Tory MPs had little influence in government.
“Tonight in the Chamber the Scottish Tories rolled over to protect their party instead of protecting the devolution settlement,” Ms Laird said.
“They gave excuses, but could offer no substantial reasons why they would not support Labour’s amendment to Clause 11.”
She added: “The Scottish Tory bloc has bragged since the general election about the influence it has on Theresa May’s government.
“This sorry episode has exposed that boast as being as hollow as the promise from the Secretary of State for Scotland.”
The SNP’s Europe spokesman, Stephen Gethins, said: “Despite all the rhetoric from the Scottish Tories, tonight their votes did not follow their voices.
“Instead, what we witnessed was a shameful abdication of duty as 13 Scottish Tory MPs marched into the lobby behind their Westminster masters.”
Mr Gethins added: “It is now clear more than ever before, that Scottish Tory MPs are mere lobby fodder willing to let this failing and faltering UK government off the hook.
“It is a democratic abomination that unelected Lords will have more of a say on devolved powers than elected MPs, or for that matter, the Scottish Parliament.”