UK's top EU diplomat resigns months before Brexit trigger
The Financial Times reported that Sir Ivan, who was appointed to lead David Cameron's renegotiation talks with the EU ahead of last year's referendum, had resigned from his role just months before the Government is due to trigger Article 50 in March.
Sir Ivan provoked anger among pro-Brexit figures at the end of 2016 by warning the Government that EU leaders believe a post-Brexit trade deal could take a decade to finalise and that even then may fail to get ratified by member states.
He also said European leaders believe the Brexit deal is likely to be a free trade arrangement rather than continued single market membership.
His warnings relating to the potential timeframe for a Brexit trade deal are believed to have caused relations to strain with some members of the Government.
The Financial Times said Sir Ivan told staff on Tuesday of his decision to step down ahead of his original departure date set for November. The BBC reported that the Foreign Office had confirmed the resignation, but had not given any reasons for the decision.
Meanwhile, his advice prompted some pro-Leave Tory MPs to label him a "gloomy pessimist".
Labour former shadow foreign secretary and chairman of the Commons Brexit Committee Hilary Benn told the BBC the resignation was "not a good thing".
"I think that it means that the Government will have to get its skates on to make sure there is a replacement in place so he or she can work with Sir Ivan in the transition, the handover," he said.
"But the hard work is going to start very soon, because if Article 50 is triggered, as the Government says it wishes to, by the end of March, then negotiations will probably begin shortly thereafter.
"And having a handover in the middle of that, depending on when exactly he goes, is not ideal."