Career diplomat Sir Tim Barrow – described by one former colleague as "experienced, skilful and resilient" – has been appointed as the UK's new ambassador to Brussels, following the dramatic resignation of Sir Ivan Rogers.
Barrow served as the UK's ambassador to Moscow until 2015, and was last year made political director of the Foreign Office.
He joined the FCO in 1986, and has served in a number of senior roles, including head of the FCO's Russia section and first secretary of the UK's Representation to the EU, based in Brussels.
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His appointment was announced late on Wednesday, and was immediately welcomed by former Foreign Office colleagues.
Sir Simon Fraser, the former permanent under-secretary at the FCO, told CSW Barrow was an "excellent choice" for the job.
"He is an experienced, skilful and resilient diplomat with real expertise on EU matters from his two postings in Brussels," said Fraser, who led the FCO from 2010 to 2015 and now works for advisory firm Flint Global.
"He was a very successful ambassador in Moscow during a tough period. He is well known and respected in Brussels, and also by ministers and colleagues in Whitehall. Tim has all the character, skills and good humour to succeed in this challenging job.”
Tom Fletcher, the UK's former ambassador to Lebanon and a visiting professor at the FCO's Diplomatic Academy, meanwhile described Barrow's appointment as "great news".
"Tenacious, human, expert, connected, thick skinned enough not to worry about nutters, and will avoid poison in the chalice," Fletcher posted on Twitter.
Cabinet secretary Sir Jeremy Heywood praised Barrow as a "hugely experienced and tough negotiator", while foreign secretary Boris Johnson said the new ambassador's "energy, wise counsel and steadfast commitment" meant he was "just the man to get the best deal for the UK".
But Theresa May's choice of a long-serving diplomat for the crucial post followed a bitter war of words over the impartiality of senior officials in the run up to Britain's departure from the European Union.
Brexit campaigners had lined up to welcome the earlier-than-expected exit of Rogers, who had been in post since 2013 but resigned months ahead of schedule. He used a resignation message to staff to urge them to "continue to challenge ill-founded arguments and muddled thinking" and "speak truth to power".
Leave.EU funder and chairman Arron Banks described Rogers – who reportedly warned ministers that Brexit talks could take longer than expected – as "yet another of the establishment's pro-EU old guard", while former UKIP leader Nigel Farage called for a “complete clear out” of the Foreign Office.
Others, however, leapt to the defence of the outgoing ambassador, with Fraser saying the "highly intelligent, knowledgeable and experienced" Rogers had simply "called a spade a spade" in his advice to ministers, while former FCO chief Lord Ricketts said it was the role of public officials to give ministers "fearless, unvarnished advice, the reality as they see it".
“This idea that you’ve got to have somebody who is pro-Brexit politicises the civil service in a way that we’ve never done in this country," he added.
Downing Street itself also came under fire for not appearing to doing more to defend the impartiality of the civil service, with Dave Penman, the general secretary of the FDA union, accusing May of “sitting back” as the commitment of diplomats and civil servants to the Brexit process was called into question.
Labour meanwhile said ministers had shown "complete cowardice" in the face of attacks on officials who are contractually unable to answer back.
"It is about time ministers acted responsibly and defended dedicated civil servants who are working flat out to prepare Britain for negotiations," shadow digital minister Louise Haigh told CSW.
Some Brexiteers appeared unplacated by Barrow's appointment however, with Farage taking to Twitter within minutes of the announcement to say: "Good to see that the government have replaced a knighted career diplomat with.... a knighted career diplomat."
Liberal Democrat leader Tim Farron was among the first to wish Barrow, whose appointment was approved by May on the advice of Heywood, luck in his new position.
But he joined those pushing back against this week's attacks on public officials from Leave supporters.
"It is a challenging role made harder by our government and the disgraceful attacks by leading Brexiteers on the impartiality of the civil service," Farron said.
Barrow, who is married to Alison and has two sons and two daughters, said in a statement that he was "honoured" to be stepping up as permanent representative to the EU at a "crucial time".
"I look forward to joining the strong leadership team at the Department for Exiting the EU and working with them and the talented staff at UKRep to ensure we get the right outcome for the United Kingdom as we leave the EU," he said.
Update: This article was update on January 5 to include further details of the appointment and reaction from Sir Simon Fraser