Former British Tory cabinet ministers have ramped up pressure on Theresa May by presenting her with a "Brexit blueprint" to take the country out the EU in less than two years.
The plan, which presses for a "take it or leave it" approach to Brussels, was circulated ahead of the Conservative Party leader making a speech on quitting the bloc at the Tory party conference on Sunday.
Mrs May has previously said she would not rush to show "rapid progress" in Brexit negotiations, insisting the process should be "sober and considered".
She has already stated that Article 50, the formal mechanism for Britain leaving the EU, will not be triggered this year.
However, the so-called Route Map for Brexit, proposed by ex-ministers Iain Duncan Smith, John Redwood, Owen Paterson and Peter Lilley, presses for a swift divorce.
The blueprint, published by the Centre for Social Justice and the Legatum Institute think-tanks, calls for an immediate new law to repeal the 1972 European Communities Act, which gave legal force to the country's membership of the then European Economic Community.
The bill would convert EU law into British law to help ensure a smooth Brexit and minimise disruption to business.
REPORT: Britain could leave the #EU in less than two years, finds new LI/ @csjthinktank report https://t.co/uyWrwrNxrP pic.twitter.com/UjE5NDs6yH
— Legatum Institute (@LegatumInst) October 1, 2016
The blueprint document states: "Subsequently, it would be open to this government and its successors to scrap aspects of EU law not considered in the UK's interests."
It argues Britain could complete its withdrawal from the EU well within the two-year deadline set out in Article 50.
The plan also says Britain could either continue tariff-free trade with the EU after Brexit, but without accepting free movement of EU citizens, or trade freely under the "relatively light" World Trade Organisation standard tariffs.
It proposes a work permit and cap system to control the number of EU migrants coming to the UK.
In an interview with Sky News, Mr Redwood said: "We have offered a pretty comprehensive route map based on the plans we launched before the referendum to say, 'let's get it over with'."
He added: "I don't think you do need to negotiate very much for this at all, because you can't negotiate taking back control.
"You can't negotiate the result of the referendum. We voted to leave.
"It was very simple. That was what it said on the ballot paper. That was our decision, so now we need to do it."
The only thing that needed to be negotiated were trade relationships, Mr Redwood said.
