A second Brexit referendum would be “morally justified”, former British prime minister Sir John Major has said.

He said the concept of a second vote had difficulties and “democratic downsides”, but Brexiteers had made such “pie in the sky” promises during the campaign that a another vote should not be ruled out.

“If you look back at the Leave campaign a great many of the promises they made were fantasy promises. We now know they’re not going to be met,” he said.

“Would you buy a house without knowing the price? No, you would not. Should we finally decide to leave Europe without knowing the cost of doing so?

“And by the cost I don’t just mean to the government, to the nation, I mean to the lives of individual people in every constituency in the land.”

The ex-leader of the Conservative Party, who was interviewed on the BBC’s Andrew Marr Show, said once the cost was known, and if it was as damaging as he believed it would be, there would be a “huge amount of disillusion”.

Meanwhile, British Brexit secretary Dominic Raab has signalled the UK could refuse to pay its €39 billion divorce bill to Brussels if it does not get a trade deal, Mr Raab said there had to be “conditionality” under the Article 50 withdrawal mechanism between settling Britain’s exit payment and creating a new relationship with the EU.

Meanwhile, he indicated he was still trying to persuade all members of the Cabinet that British prime minister Theresa May’s Chequers agreement was “the best plan to get the best deal”.

Former Brexit secretary David Davis has urged the prime minister to “reset” her negotiating strategy.

In an interview with the Sunday Telegraph, Mr Raab suggested the divorce bill could be used as leverage in the talks with Brussels.

He said: “Article 50 requires, as we negotiate the withdrawal agreement, that there’s a future framework for our new relationship going forward, so the two are linked.

“You can’t have one side fulfilling its side of the bargain and the other side not, or going slow, or failing to commit on its side.

“So, I think we do need to make sure that there’s some conditionality between the two.”

Pressed on whether he would put such a provision into legislation, Mr Raab said: “Certainly it needs to go into the arrangements we have at international level with our EU partners. We need to make it clear that the two are linked.”

The comments appeared at odds with UK chancellor Philip Hammond, who said of the divorce payment last December: “I find it inconceivable that we as a nation would be walking away from an obligation that we recognised as an obligation.

“That is not a credible scenario. That is not the kind of country we are. Frankly, it would not make us a credible partner for future international agreements.”

Mr Raab also defended the controversial Chequers Cabinet compromise on withdrawal aims, insisting he wanted to persuade voters and Cabinet colleagues that it is the way forward.

The Brexit secretary said: “I want to make sure we can persuade everyone — grassroots, voters, parliamentary party and ministers, including in the Cabinet - that we’ve got the best deal and the best plan to get the best deal.”

Mr Raab said critics were mistaken to think Ms May would not walk away without a deal if she had to.

“They’re wrong. No bluffing.

“The ball is now in the EU’s court, and don’t get me wrong, there will be plenty more negotiations, I’ve made that clear, but if they show us the same level of ambition, energy, pragmatism, this deal gets done in 12 weeks.”

Mr Davis, who quit as Brexit secretary in protest at the Chequers agreement, said Ms May needed to “start again” on withdrawal plans.

“We’re going to have to do a reset and come back and look at it all again,” he told the Sunday Express.

“I think when we get to the autumn, if we are in the situation where we don’t have any degree of agreement, we’re going to have to start again.”

Mr Davis suggested the Government draws up fresh proposals based on an amalgamation of the “best bits” of deals the EU has already struck with other countries, such as Canada, South Korea, Switzerland and New Zealand.

Meanwhile, preparations for no deal need to accelerate from the current position of “consult and cajole” to “command and control”, he told the paper.

“By the end of the summer it should be plain we are making proper preparations for this,” he said.

The comments came as a new poll suggested only 16 per cent of voters think Ms May is handling negotiations well, while 34 per cent believe former foreign secretary Boris Johnson would do a better job.

And 38 per cent of people would vote for a new party on the right that was committed to Brexit, while 24 per cent are ready to support an explicitly far right anti-immigrant, anti-Islam party, according to the You Gov survey for the Sunday Times.

The poll found that one in three voters are prepared to back a new anti-Brexit centrist party.–PA