The author of Article 50 is to make a speech today accusing the Prime Minister of misleading the British public over whether or not Brexit may be reversed.

Lord Kerr of Kinlochard will condemn Theresa May for her “political decision” to fail to disclose that the UK government can unilaterally halt Brexit at any time.

His intervention comes as a fresh round of Brexit talks commences in Brussels with no progress on issues including the Irish border and the rights of EU citizens.

In a speech at the Open Britain event in London, Lord Kerr will say: “The fact is that a political decision has been made, in this country, to maintain that there can be no going back.

“Actually, the country still has a free choice about whether to proceed.

“As new facts emerge, people are entitled to take a different view. And there’s nothing in Article 50 to stop them.

“I think the British people have the right to know this – they should not be misled.”

Lord Kerr, formerly Britain’s permanent representative at the EU before he was made ambassador to the US, will add: “The government give the impression that the Rubicon has been crossed, but they currently refuse to publish their law officers’ opinion: I think we know why.

“They have been careful not to say that we could not take back Mrs May’s letter.

“During the Miller case, and at the Despatch Box in both Houses, government spokesmen have consistently said only that “as a matter of firm policy”, we won’t take it back.

“That formula in itself confirms that we could take it back.”