Lord Kerr says EU treaty allows UK to change mind up to moment of leaving, and adding date to bill would not change that

The former diplomat who drafted article 50 says the UK could opt to reverse Brexit up to the moment we leave, even if a date for the country’s departure from European Union were added to the withdrawal bill, as Theresa May plans.

Lord Kerr, a former UK ambassador to the European Union, said Brexiters in May’s cabinet were suggesting Brexit was irreversible and thereby misleading the public.

He was speaking hours after the government confirmed it wanted an amendment to the withdrawal bill to set a fixed departure point of 11pm GMT (midnight in Brussels) on 29 March 2019.

“We are leaving the European Union on 29 March 2019,” May wrote in the Telegraph.

Speaking on BBC Radio 4’s Today programme Kerr, now a crossbench peer, said the UK could still opt to stay in the EU. “At any stage we can change our minds if we want to, and if we did we know that our partners would actually be very pleased indeed.”

He added: “The Brexiters create the impression that is because of the way article 50 is written that having sent in a letter on 29 March 2017 we must leave automatically on 29 March 2019 at the latest. That is not true. It is misleading to suggest that a decision that we are taking autonomously in this country about the timing of our departure, we are required to take by a provision of EU treaty law.”

His complaint came as the Brexit secretary, David Davis, and the EU’s chief negotiator, Michel Barnier, prepare to meet in Brussels on the second day of the latest round of talks before a crunch summit of European leaders next month.

Facebook Twitter Pinterest Lord Kerr: ‘It is always possible at a later stage to decide that we want to do something different.’ Photograph: Ian Nicholson/PA

Kerr was asked to clarify whether the UK could still halt Brexit even if a date was set on the face of the EU withdrawal bill. “That’s what I’m saying,” he said. Speaking before a speech to an Open Britain event later on Friday, he added: “One should bear in mind that it is always possible at a later stage to decide that we want to do something different.”

He added: “It is entirely up to the prime minister to set a date for our departure. My point is quite a different one. These decisions are taken entirely in this country, they have nothing to do with the treaty. As far as the treaty is concerned there are lots of options. There is a provision to seek some extra time for negotiation and, much more important, there’s the ability at any stage to take back the letter that the prime minister sent to President Tusk on 29 March.”

Kerr was asked about Davis’s view that the referendum result was a an “irrevocable moment”. He replied: “The David Davis quote I would offer you comes from 2012 when he said: ‘A democracy that has lost the right to change its mind has ceased to be a democracy.’”

He added: “I’m not a politician. I’m just the guy who wrote the treaty telling you what the treaty means.”

Kerr claimed that circumstances had changed since the referendum.

He said: “It is open to us to argue that the terms as they emerge are not quite the ones that we were led to expect: that the costs of coming out are rather different from what it said on the side of the battlebus; that the complexity of coming out was not entirely explained and the effects of coming out on, for example, the NHS or jobs, these things are not what the electorate knew about at the time. If new facts emerge one is entitled to change one’s view, as Keynes said.”

He added: “I’m not today arguing for a second referendum, I’m saying if we wanted to have a second referendum there is nothing in the treaty, or in the attitude of EU partners, that would prevent us taking the time to have one.”