Theresa May has refused to commit to giving MPs a vote on her Brexit strategy despite growing Tory calls for more clarity on the plan before the formal process of leaving the European Union is triggered.

During a tumultuous day's trading, the pound made a cautious bounce back as the Prime Minister allowed Tories to back a Labour call for "proper scrutiny" of the strategy in a bid to head off a potential backbench rebellion.

Crucially, Labour's motion debated by MPs on Wednesday, does not echo cross-party calls for a vote on the Brexit plan before Article 50 of the EU treaties is triggered by the end of March, and is not binding on ministers.

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The PM was therefore able to allow disgruntled Tories, who want a vote, to back the Labour motion without rebelling, by voting for a Government amendment which simply adds caveats.

Despite Mrs May's insistence that her position has not changed, City analysts said the prospect of greater parliamentary scrutiny appeared to give sterling some respite.

But the pound's modest rally did later stumble as Brexit Secretary David Davis responded to Labour's motion in the House of Commons.

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Mr Davis said he could not go into detail about the Government's negotiating strategy and would not reveal whether it was pursuing a "hard Brexit" strategy outside the single market.

Connor Campbell, financial analyst at Spreadex, said: "In the face of US investors keen to buy the dollar as Donald Trump's presidential campaign disintegrates, and a speech from Brexit minister David Davis that erred on the 'hard' side of things, the pound managed to rise 0.7% against the greenback and 0.8% against the euro this Wednesday.

"A slight comedown from its morning highs, then, but nevertheless the kind of respite sterling was crying out for by the end of yesterday's trading."

Kathleen Brooks, research director at City Index, said: "If Parliament can debate the plans, then the Prime Minister may have to soften her approach to negotiations, which could remove some of the market fears about the negative economic impact of Brexit."

During the debate, more backbench Tory MPs joined the calls for greater clarity in order to protect British jobs, businesses and investment.

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Former minister Claire Perry said she was "extremely concerned" about the pound's overall poor performance over the last week and Chris Philp asked for as much clarity as possible over the likely future trading arrangements.

They spoke as Tory former attorney general Dominic Grieve renewed his call for the Commons to be given a vote on the Brexit plan before Article 50 is invoked, an idea which also has the support of pro-Leave Tory MP Stephen Phillips.

But asked at Prime Minister's Questions if her concession to Tory MPs would mean a Commons vote before invoking Article 50, Mrs May replied: "The idea that Parliament somehow wasn't going to be able to discuss, debate, question issues around (Brexit) was frankly completely wrong.

"Let me give you some examples - first of all the Secretary of State for Exiting the European Union has already made two statements in this House, I believe four hours of questions followed from those.

"A new select committee has been set up which crucially includes representatives from all parts of the United Kingdom, which will be looking at these issues.

"And only just over a week ago, I announced there would be a Great Repeal Bill in the next session of Parliament to repeal the European Communities Act.

"So Parliament's going to have every opportunity to debate this issue."

At PMQs, Jeremy Corbyn said Mrs May was pursuing "shambolic Tory Brexit" to appease her backbenchers as Labour posed the Government 170 questions on Brexit - one for every day until Mrs May's deadline for triggering Article 50.

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The Labour leader said the Government offers "no strategy for negotiating Brexit and offers no clarity, no transparency and no chance of scrutiny of the process for developing a strategy".

Asked whether Mr Corbyn believed MPs would be given a vote on Mrs May's negotiating stance, the Labour leader's spokesman told reporters: "The Government has already U-turned today and I think the pressure is clearly growing for proper accountability over what this Government's negotiating position is on Brexit.

"As Jeremy said in the House today, Labour completely accepts and recognises the vote to leave the EU. The question is what is the agenda for that process and that needs to be held to account in Parliament now and that means it needs to be open to a vote."

Meanwhile, the Open Britain campaign highlighted 2008 comments in which Mrs May backed parliamentary votes to define Britain's negotiating position in the EU.

"We should have a statutory scrutiny reserve so that ministers would have to gain parliamentary approval before negotiations in the Council of Ministers," she told the Commons on February 7 2008.

"The system would also need to be backed by clear sanctions so that if the minister broke the reserve - if he or she came to an agreement with the committee and went on to negotiate a different position -there could be some kind of formal censure."

Commenting for Open Britain, Labour MP Phil Wilson said: "The Government's negotiating hand would be strengthened if they had clear plans backed by a strong parliamentary mandate.

"This is something the Prime Minister used to support. I hope ministers will now listen to MPs on all sides and give Parliament a vote on the terms of their Brexit negotiation