Sir Kim Darroch has resigned as the UK ambassador to the US over a row between President Donald Trump and leaked memos.
Sir Kim had called President Trump “inept” in secret memos that were leaked causing an unprecedented row between Washington and Westminster.
MPs are calling for a police investigation as the leaked memo is a breach of the Official Secrets Act, to which only a few people would have access.
Sir Kim said the leaked memo has made “it impossible for me to carry out my role as I would like.”
Sir Kim wrote a letter to Sir Simon McDonald who is the permanent under secretary at the Foreign Office.
He wrote, “Since the leak of official documents from this Embassy there has been a great deal of speculation surrounding my position and the duration of my remaining term as ambassador. I want to put an end to that speculation.
“The current situation is making it impossible for me to carry out my role as I would like.
“Although my posting is not due to end until the end of this year, I believe in the current circumstances the responsible course is to allow the appointment of a new ambassador.”
Sir Kim added, “I am grateful to all those in the UK and the US, who have offered their support during this difficult few days. This has brought home to me the depth of friendship and close ties between our two countries. I have been deeply touched.
“I am also grateful to all those with whom I have worked over the last four decades, particularly my team here in the US. The professionalism and integrity of the British civil service is the envy of the world. I will leave it full of confidence that its values remain in safe hands.”
In a series of tweets posted by Trump he called Darroch “a very stupid guy” after he was called “clumsy and inept.”
Trump said on Tuesday that Theresa May had ignored his advice over Brexit and said she had gone her “own foolish way.”
Jeremy Hunt MP hit out at Trump and tweeted, “Friends speak frankly so I will: these comments are disrespectful and wrong to our prime minister and my country.”
May said the resignation of Darroch was a “matter of great regret.”
Speaking to the Commons she added, “The whole Cabinet rightly gave its full support to Sir Kim on Tuesday.
“Sir Kim has given a lifetime of service to the United Kingdom and we owe him an enormous debt of gratitude.
“Good government depends on public servants being able to give full and frank advice.
“I want all our public servants to have the confidence to be able to do that and I hope the House will reflect on the importance of defending our values and principles, particularly when they are under pressure.”