The UK’s permanent representative to the European Union, Sir Ivan Rogers, has resigned from his post, triggering a bitter war of words over the government's Brexit strategy.
According to the Financial Times, Rogers on Tuesday told Foreign Office staff that he would be quitting as the UK's top EU diplomat, but gave no reason for his departure. It is understood that he had originally been due to stay on until the autumn.
A government spokesperson has since confirmed the resignation, which comes just months before Britain is expected to trigger Article 50 and begin formal exit talks with the 27 other EU member states.
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In a statement, the spokesperson said: "Sir Ivan Rogers has resigned a few months early as UK Permanent Representative to the European Union.
"Sir Ivan has taken this decision now to enable a successor to be appointed before the UK invokes Article 50 by the end of March. We are grateful for his work and commitment over the last three years."
Rogers, who started his civil service career in the Treasury and also served as principal private secretary to Tony Blair in Number 10, was appointed to the post in November 2013, after a stint as head of the powerful European and Global Issues Secretariat.
He formed a key part of David Cameron's team during the then-prime minister's bid last year to renegotiate the terms of the UK's EU membership ahead of the referendum.
News of his departure comes after confidential advice he gave to ministers was leaked to the press.
According to reports, Sir Ivan had warned ministers that EU member states believed a post-Brexit trade deal with the UK could take up to a decade to finalise and could even be rejected by individual parliaments.
That assessment saw him come under fire from some pro-Brexit politicians, and the billionaire Leave.EU chairman Arron Banks on Tuesday criticised Rogers for being "yet another of the Establishment's pro-EU Old Guard".
"He has at least done the honourable thing in resigning," Banks added. "It's time now for someone who is optimistic about the future that lies ahead for Brexit Britain."
Nigel Farage, the former UK Independence Party leader, went a step further and called for a "complete clear out" of the Foreign Office.
But those who have worked with Rogers leapt to his defence. Former Treasury permanent secretary Sir Nicholas Macpherson reacted to the departure by hitting out at the government's "wilful and total destruction of EU expertise".
Ivan Rogers huge loss. Can't understand wilful&total destruction of EU expertise, with Cunliffe,Ellam&Scholar also out of loop.#amateurism
— nick macpherson (@nickmacpherson2) January 3, 2017
Nick Clegg, the former deputy prime minister, meanwhile said the resignation seemed to be part of a "very worrying trend" of attacking public officials since the Brexit vote.
“First it was the judges, condemned as enemies of the people for just doing their jobs," he told The Guardian.
"It’s been the CBI and any business that didn’t sign up to the Brexit zeal, and now it’s senior officials being kneecapped in the Brexit press, after Sir Ivan Rogers just gave candid advice about the length of time negotiations might take."
Jill Rutter, programme director of the Institute for Government think tank and a former Treasury official, said that while Rogers had "always" been planning to leave in October 2017 – a problematic leaving date given this year's French and German presidential elections and the planned triggering of Article 50 – it was "not a great time for change" at the UK Representation to the EU.
"Although the Department for Exiting the EU is about to be strengthened by the arrival of an additional director general – Alex Ellis, fresh from his post as Ambassador to Brazil – UKRep is already scheduled to lose Rogers’ number 2, Shan Morgan, who will become permanent secretary in Wales," she wrote on the IfG's blog.
"To lose the top two officials at the same time, risks the loss of big networks of contacts and potential capital assembled over years which could have been useful in negotiations."
Update: This story was updated on January 3 to include a full government statement and incorporate Sir Nicholas Macpherson's remarks in the headline