Existing deal is "only option" for "orderly" Brexit

He also blamed the Brexit referendum vote on “nostalgia for the past”, saying France has "the same problems".

Speaking to The New York Review of Books, Michel Barnier said if the UK chooses one of the other options, “fine”, but if it wishes an “orderly” exit then the existing withdrawal agreement is “all that our legal constraints allow”.

If it goes ahead then the EU stands ready to immediately start negotiations on the future relationship, which would be “much more interesting” than the “divorce” talks, Mr Barnier said.

This would include trying to organise systems for the Northern Ireland border that would avoid the need for the so-called “backstop” of the UK remaining in a customs union.

This might involve “technology, drones, invisible controls”, he said. However he said it would take time to put the required infrastructure in place.

Mr Barnier said it would be up to the European Commission to decide if he should lead those negotiations. His ambition was simply to “remain useful”.

He gave the same diplomatic response when asked if he would like to be the new Commission president, when there is a change of Commission from the start of November this year.

He is thought to be a serious candidate for the job.

Asked about the EU’s future, Mr Barnier said it remained vital for the European countries to speak as one on trade and competition if they are to hold their own in the world.

However at the same time people must be reassured that their cultural roots will be respected, he said.

Speaking of Brexit, he confirmed that current EU Commission president Jean-Claude Juncker regrets not intervening in the referendum campaign “to correct some of the lies that were told”.

However the reasons for Brexit “run deeper”, he added.

“We have to take into account the popular sentiment in Britain. For Britain, it’s probably too late, but it’s not too late for other countries where we have exactly the same problems, including my country [France].

Looking at the causes of Brexit, we also find typically British reasons: the hope for a return to a powerful global Britain, nostalgia for the past—nostalgia serves no purpose in politics.

“In my country, too, some politicians still prefer to live in the past.”

He said another reason for Brexit was that some of those working in finance in the City of London did not want to accept EU regulations on trading.

Another was that some people had felt “abandoned”, and had felt services, healthcare and transport were worsening.

“We must listen to these fears and address them,” he said.