Justine Greening became the most high profile Conservative to endorse the idea of a second referendum, to end what she said would be a likely parliamentary deadlock over Brexit, warning that Theresa May’s Chequers plan did not represent “a workable compromise” that a majority of MPs could get behind.

The former education secretary and remain supporter said that Ms May’s plan was “a fudge I can’t support” and, in a blow to the prime minister, said it amounted to “the worst of both worlds” - complying with EU rules without the influence of being a member of the multi-country bloc.

Writing in the Times, the MP for Putney said that “only solution is to take the final Brexit decision out of the hands of deadlocked politicians”.

She added that voters should be given three options on the ballot paper, and a first and second preference vote to ensure that the preferred model achieved more then 50 per cent of the final vote.

The choice should be between “the PM’s final negotiated Brexit deal, staying in the EU, or a clean Brexit break and leaving with no deal”, Greening wrote in a break from her party’s position that is likely to be picked up by the campaign groups seeking to overturn Brexit with a second referendum

Unhappiness from the Tory right over May’s proposed Brexit deal, and their threats to vote it down when a promised meaningful final vote is put to parliament around the turn of the year, have prompted growing speculation that the prime minister may struggle to ensure whatever she negotiates will be approved by parliament, placing Britain’s future relationship with Europe in limbo.

Other high profile figures have started to use the belief that there is political deadlock to advance arguments for a second referendum.

On Sunday, Tony Blair said in a post on the website for his Institute for Global Change that there should be another national vote, because there will no Commons majority for May’s Brexit, a no deal Brexit, or for remaining in the European Union.

Blair also hinted there should be three choices for voters: “The question may be complicated because it really involves three choices: Clean Break, ‘soft’ or stay. But the complexity is not insuperable,” he said. – Guardian