Brexit: Theresa May promises to reveal 'negotiating priorities' in speech amid criticism over approach to EU withdrawal

It comes as an exclusive poll for The Independent suggests people are unconvinced by her handling of Brexit

Theresa May will finally try to kill criticism that her Brexit vision is too vague by setting out a list of her "negotiating priorities" for EU withdrawal talks.

Downing Street sources said today’s long-anticipated speech from the Prime Minister will shed new light on the critical question of Britain’s single market membership and the EU customs union.

But critics in her own party who have attacked Ms May’s ambiguous approach to date piled on the pressure by warning of “big problems” if she fails to give real detail of her approach ahead of an expected Commons vote on launching Brexit talks.

The major speech also comes as an exclusive BMG Research poll for The Independent revealed more people believe Ms May is handling Brexit preparations badly than well.

Ms May’s enigmatic speeches and interviews on Brexit up to now have been met with constant claims that she has no real Brexit plan, but in the speech at Lancaster House she has promised to set out “12 negotiating priorities and the four key principles driving them”.

She will say: “We have 12 objectives that amount to one big goal: A new, positive and constructive partnership between Britain and the European Union.

“And as we negotiate that partnership, we will be driven by some simple principles. We will provide as much certainty and clarity as we can at every stage. And we will take this opportunity to make Britain stronger, to make Britain fairer, and to build a more global Britain too.”

To date the Prime Minister has rejected interpretations of her words that suggest she is taking the UK towards a hard Brexit, with the UK leaving the single market and customs union, by claiming she does not even recognise the term. But extracts of her speech will further fuel speculation over the matter.

She will say: “We seek a new and equal partnership – between an independent, self-governing, global Britain and our friends and allies in the EU.

“Not partial membership of the European Union, associate membership of the European Union, or anything that leaves us half in, half out. We do not seek to adopt a model already enjoyed by other countries. We do not seek to hold on to bits of membership as we leave.

“The United Kingdom is leaving the European Union. My job is to get the right deal for Britain as we do.”

A No 10 insider said the speech would bring more clarity to questions over the single market and customs union, but some MPs were not convinced.

Over the next two weeks the Supreme Court is set to rule whether Ms May must give Parliament a vote on triggering Article 50, something even ministers expect it to do.

MPs have been promised details of her approach to Brexit to inform the vote. But many were expecting a separate document in addition to Ms May’s speech, which they suspect will be nebulous.

With No 10 sources suggesting Ms May’s speech will be all they get, one senior Tory backbencher told The Independent: “If Downing Street think that this speech is going to be the plan that will be voted on by the House of Commons they will have big problems with that.

“A bunch of us will take a very dim view of that and the Labour party is expected to as well. They promised a plan, a speech is not a plan.”

Another Tory MP demanded more clarity over the Prime Minister's approach to the single market, adding: “If it’s this idea that we leave and arrange preferential access for certain sectors, then which?

“If it’s cars or pharmaceuticals, then what about other industries? What about aerospace, for which parts of their products are manufactured all over Europe? The customs union is important to them too. That’s what we mean by certainty.”

Conservative MP Neil Carmichael, a leading supporter of the Open Britain campaign, said: “The Prime Minister’s commitment to trading as freely as possible with the EU is welcome, but the best possible trading arrangement with the EU is full participation in the single market.

“No other arrangement is comparable, and so if the Government abandons membership of the single market, they will start the negotiations opting for second best.”

Tory peer Patience Wheatcroft, who has led calls for Parliament to have more say on Brexit, said: “I’m not expecting a great deal of detail beyond ‘control of our borders’ and ‘we will be looking for the best possible terms of trade within the single market’.

“There will no doubt be quite a lot about what good news it is that President-elect Trump is keen to see us doing a lot of business with the US, but that doesn’t amount to a great deal. I would like to hear we won’t be triggering Article 50 until after the French and German elections, because what’s the point until you know who will be on the other side of the table? I hope, but don’t expect, that she will promise a vote in Parliament on the terms of the deal she gets.”

An exclusive poll for The Independent by BMG Research found that when people were asked, “In your opinion, is Theresa May doing a good job, or bad job, preparing the UK for Brexit?", just 25 per cent said she is doing a “good” or “very good” job.

Meanwhile almost a third, 30 per cent said she is doing a “bad” or “very bad” job, 27 per cent said she is doing average and 18 per cent said they did not know.

Last night a YouGov poll also showed more people supported some form of soft Brexit, 47 per cent, than the hard Brexit approach apparently being pursued by the Prime Minister, which had the support of 30 per cent of those surveyed.

Chancellor Philip Hammond has indicated the UK could become a 'tax haven economy' on the shores of the European Union (Reuters)

Ms May’s speech also comes after Chancellor Philip Hammond suggested in an interview that Britain could transform its economic model into that of a corporate tax haven if the EU fails to provide it with an agreement on market access after Brexit.

Labour's shadow Brexit secretary Sir Keir Starmer told The Independent: "Tomorrow the Prime Minister has the chance to finally provide some clarity over her Brexit strategy and reassure the country.

"Having spoken to businesses, trade unions and communities across the UK it is clear what they need to hear; that the Prime Minister will put jobs and the economy first, ensure companies are able to trade without tariffs or additional impediments, that there will be no watering down of key employment or environmental rights; and that we will form a new cooperative relationship with the EU. That is an ambitious approach to Brexit but we should expect nothing less.

"The Prime Minister also needs to recognise that a one-off speech is not the same as a plan for Brexit. The House of Commons voted overwhelmingly for a Brexit plan to be published before Article 50 is triggered and Labour will hold the Government to it."

Liberal Democrat leader Tim Farron claimed the kind of Brexit Ms May is exploring would be “destructive”.

He said: “Hard Brexit and the consequences will be felt by millions of people through higher prices, greater instability and rising fuel costs.

“Theresa May can say everyone must come together, but when she delivers a message like this no one will believe her.”