Britain's ambassador to the European Union unexpectedly quit on Tuesday, just weeks before the UK is set to begin the formal process of leaving the EU, meaning his replacement will have just weeks to settle in before beginning negotiations.
Sir Ivan Rogers had helped conduct David Cameron's renegotiation of Britain's EU membership, which was rejected by voters in last year's referendum. He had been expected to stay in the job until November but relations with Theresa May's team appeared strained.
Lord Macpherson, the former senior civil servant who led the Treasury until last year, said it was a "huge loss" and attacked the "wilful and total destruction of EU expertise" ahead of forthcoming negotiations on a new deal between London and Brussels.
Ivan Rogers huge loss. Can't understand wilful&total destruction of EU expertise, with Cunliffe,Ellam&Scholar also out of loop.#amateurism
Macpherson, who was at the heart of government for over a decade, suggested other key civil servants with EU knowledge were "out of the loop" before finishing with the hashtag "#amateurism".
Rogers' resignation, first reported by the Financial Times, appeared to catch the government by surprise. After several hours the Foreign Office issued a statement portraying the decision to quit as a way of streamlining the Brexit process.
“Sir Ivan Rogers has resigned a few months early as UK permanent representative," said a spokesperson. "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."
However, it was not clear why Rogers chose to quit in January when the timetable had been known for several months. He had received criticism in December for being too pro-Remain after a leaked memo appeared to suggest he felt a post-Brexit trade deal could take a decade to negotiate and then still fail.
Reaction to his resignation was split along the lines of the referendum: Leave voters celebrated Rogers' departure and criticised him for being an EU insider, while Remain voters complained the UK had lost one of the few representatives who know how Brussels works.
I welcome the resignation of UK ambassador to Brussels, Ivan Rogers. The Foreign Office needs a complete clear out.
Nick Clegg, the former Lib Dem deputy prime minister, said it was a "body blow to the government's Brexit plans".
"If the reports are true that he has been hounded out by hostile Brexiteers in government, it counts as a spectacular own goal."
Theresa May is due to formally invoke Article 50, beginning the two-year process of Britain leaving the EU, by the end of March.