Britain can still cancel Brexit, the man who wrote Article 50 has declared.
Lord Kerr, who played a central role in drafting the EU treaty clause that triggered Brexit , says the “die is not irrevocably cast”.
His intervention comes as Theresa May jets into Salzburg for a crunch Brexit showdown with EU leaders.
In a new report, published today, Lord Kerr claims Britain’s Article 50 letter can legally be withdrawn.
He suggests parliamentarians have six opportunities on the horizon to force the Government to legislate for a people’s vote on the terms of the Brexit deal.
And it insisted that the option of staying in the EU “must be on the ballot paper”.
Such a referendum, the report suggests, would have a binary choice on the ballot paper – either Theresa May’s deal versus stay, or if the Government fails to reach a deal, no-deal versus stay.
And it suggests there would be “no difficulty” rewriting the Article 50 timetable to give more time to push through a people’s vote.
The crossbench peer, who was Secretary-General of the European Constitutional Convention, says his work has been based upon conversations with a string of legal experts, including former Attorney General Dominic Grieve.
Lord Kerr said: “Given the gravity of the situation our country and our democracy are facing, it is important that no decisions are made in haste.
“And yet we do not have the luxury of time. Of course, it will ultimately be for our elected representatives to determine the precise route to a People’s Vote and the mechanics by which it would operate.
“Equally, the urgency of this crisis means that these decisions should prioritise speed, clarity and simplicity at every stage.”
He added: “Indeed, to waste time or to do nothing are perhaps the worst options of all.
“History will not, in our opinion, be kind to any politician who hides behind purely logistical arguments, legalese or arcane parliamentary procedure in order to deny people a vote on the outcome of these Brexit negotiations at such a fragile and crucial moment for our country.”
Best for Britain chief Eloise Todd said: “This serves as a good reminder that it’s not too late for the country to take a different course.
“This chimes well with the road map we set out in June to secure a vote that allows people to compare the government’s deal with our current EU membership terms.”
It comes as Prime Minister Theresa May heads to Salzburg for a showdown with EU leaders.
The Prime Minister will use a dinner in the Austrian city to urge bloc chiefs to back her withdrawal blueprint.
She is set to call on fellow leaders to compromise and support her Chequers proposal, which was agreed by Cabinet at the PM’s country retreat, a senior No 10 official said.
Mrs May is expected to argue that “to come to a successful conclusion, just as the UK has evolved its position, the EU will need to do the same”.
She is due to say that with “goodwill and determination on both sides we can avoid a disorderly exit and reach a deal that is in the best interests of both sides”.
EU leaders will be told that “neither side can demand the ‘unacceptable’ of the other, such as an external customs border between different parts of the United Kingdom – no other country would accept it if they were in the same situation”.
With the future of Northern Ireland’s border with the South – which also forms the UK’s only land frontier with the EU – under scrutiny, she is expected to pledge to “honour our commitment to ensure that there is a legally operative protocol on Northern Ireland”.
But it must respect the 1998 Good Friday Agreement which largely brought peace to Northern Ireland and be one which “respects the constitutional and economic integrity of the UK”.
The PM is set to insist she realises it would be “unacceptable” for Britain to “seek the rights of EU membership without the obligations”.
She is expected to say: “What we are proposing is a fair arrangement that will work for the EU’s economy as well as the UK’s, without undermining the single market.
“This would be balanced by a strong security relationship to keep all our citizens safe from threats at home and abroad.”