The Brexit deal Prime Minister Theresa May is struggling to get through Parliament includes a 21-month transition in which European Union trading arrangements would be little-changed, though it's still up to partner countries - including Japan and South Korea - to decide whether they want to roll over their agreements with the European Union to the United Kingdom, which will technically have left the bloc.
British Prime Minister Theresa May is set to return to Brussels on Wednesday in a new effort to re-open the terms of the Brexit divorce deal.
European Commission president Jean-Claude Juncker said today that Brexit is "the past" and that he has "Brexit fatigue".
Mrs May was in Brussels last night for further talks with Mr Juncker in yet another attempt to wrestle concessions out of the EU.
Business Secretary Greg Clark said the United Kingdom isn't likely to reach agreements with Japan and South Korea to roll over existing trade deals before Britain's scheduled departure from the European Union on March 29.
"Time is of the essence, and it's in both our interests that when the United Kingdom leaves the European Union it does so in an orderly way".
"If you have a time limit or a unilateral exit clause, you no longer have a genuine backstop".
A spokesman for May called the Brussels trip "significant" as part of a process of engagement to try to agree on the changes her government says parliament needs to pass the deal.
"Our message has been clear - you need to assess the impact of Brexit on your business and take the necessary action now, to mitigate the challenges that Brexit undoubtedly brings", said Lynda Slattery. "Brexit is the past, it is not the future", he said to the committee.
The UK has admitted it will not be able to sign a trade deal with Japan that matches the EU's own agreement before the 29 March Brexit deadline.
"It is clear that leaving the European Union without a deal would deliver a damaging short-term shock and would undermine our future prosperity and security - and in my view that would represent a betrayal of the promises about Brexit that were made during the referendum campaign".
"If no deal were to happen, and I cannot exclude this, this would have awful economic and social consequences in Britain and on the continent, so my efforts are oriented in a way that the worst can be avoided".
A joint statement issued following the meeting said: "The two leaders agreed that talks had been constructive and they urged their respective teams to continue to explore the options in a positive spirit".
The statement said discussions had looked at "which guarantees could be given with regard to the backstop that underline once again its temporary nature and give the appropriate legal assurance to both sides".
Mr Barclay and Attorney General Geoffrey Cox were said to have had a "productive" discussion with the EU's chief negotiator, Michel Barnier, in the Belgian capital on Monday.
Both sides have said they want to avoid this, and many experts foresee economic chaos, even warning of food and medicine shortages or a renewed threat of unrest in Northern Ireland.
Expectations had been low before Juncker and May met for their latest round of Brexit talks on Wednesday.
He played down the idea of the EU reopening the current withdrawal treaty, saying: 'The EU's position is that the treaty won't be reopened but can be interpreted or complemented with explanations that may be satisfactory'.