The former Foreign Secretary said he backed a managed withdrawal from the EU, as advocated by the Chancellor, Philip Hammond, which he described as having “immense attractions”.
Mr Hammond’s transition strategy of retaining free movement of labour until 2022 appears to have triggered a split in Theresa May’s Cabinet between those defending a soft Brexit and Eurosceptic hardliners.
The plan for an ”implementation” phase would also see the UK seeking to stay in the EU single market and customs union for three years after leaving the bloc.
“This is seen by longstanding advocates of leaving as a ‘soft’ position or a climbdown. But in reality it is a plan to rescue Brexit from an approaching disaster,” Lord Hague said.
The former Tory leader was unequivocal when it came to stressing the risks the UK is taking as it prepares to exit the EU, including an economic downturn, instability for businesses, the difficulty to pass the final terms of the withdrawal deal in Parliament and the prospect of leaving the EU without an agreement altogether.
He wrote: “Take all these risks together and there is the clear potential for Brexit to become the occasion of the greatest economic, diplomatic and constitutional muddle in the modern history of the UK, with unknowable consequences for the country, the Government and the Brexit project itself.”
He argued that a transitional deal would make the negotiations with the EU easier and quicker, partly solving the row over the UK footing EU bills as it would keep making budget payments until 2021. It would also grant UK negotiators more time to set up a new customs system.
Lord Hague noted that fewer new laws would be needed in the short term, easing the pressure on businesses having to make decisions over jobs and income and making it more likely a united Government would succeed in passing through Parliament the terms of Britain’s departure.
Mr Hammond is understood to have the backing in Cabinet from the Home Secretary, Amber Rudd, and First Secretary, Damian Green.
But Mr Fox has rubbished the idea that Cabinet had agreed to allow free movement of labour three years after Brexit, saying any such move would “not keep faith” with the referendum result.
In the column, Lord Hague also revealed business leaders and politicians asked him how the UK would “get round” the EU referendum result. He claims he was asked the question “for months ... everywhere I went abroad”.
“I explained to them that this really is a democracy. The electorate voted to leave the EU, and therefore we leave,” he said.
He said that, like his former colleagues who voted Remain, he had to accept the result. But he warned both Brexiteers and the Government that underestimating the challenges ahead could see people turn against them and change their mind on Brexit.
“Now, there is a fresh danger that, with the referendum behind them, the enthusiasts for Brexit will underestimate the dangers that things could go so badly wrong that the country turns against the people trying to deliver what it voted for, or event the idea itself,” he wrote.
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies