The UK ambassador to the US, Sir Kim Darroch, was tasked with compiling a briefing note on Donald Trump's personality and leadership style just a few months after he became President.
Below are some of the highlights of that leaked memo that could prove embarrassing for the Foreign Office.
On Trump's personality
"For a man who has risen to the highest office on the planet, President Trump radiates insecurity."
"There is no filter. And we could also be at the beginning of a downward spiral, rather than just a rollercoaster: something could emerge that leads to disgrace and downfall."
"I don't think this Administration will ever look competent."
More from Donald Trump
"As seen from here, we really don't believe that this Administration is going to become substantially more normal; less dysfunctional, less unpredictable, less faction-riven. Less diplomatically clumsy and inept."
"The stories about White House knife fights are, we judge, mostly true: multiple sources and confirmed by our own White House contacts. This is a uniquely dysfunctional environment."
On cancelled Iran airstrike
"His claim, however, that he changed his mind because of 150 predicted casualties doesn't stand up; he would certainly have heard this figure in his initial briefing.
"It's more likely that he was never fully on board and that he was worried about how this apparent reversal of his 2016 campaign promises would look come 2020 [at the next election]."
How to deal with the president
"You need to start praising him for something he has done recently. You need whenever possible to present them as wins for him."
"A senior White House adviser told me, there is no upside with this President in being subtle, let alone ambiguous."
"Arguably, you get more respect from this President if you stand up to him occasionally – provided the public comments do not comeRead More – Source