Who leaked the US ambassador’s thoughts on Trump?

Politics Explained: A massive inquiry is under way in Whitehall for the source of revelations which threaten to undermine UK diplomacy

US president’s administration was described as ‘inept’ in emails (AP)

For many in Westminster, the shocking element to Sir Kim Darroch’s cables is not their contents – which echo the views of many Washington-watchers on the nature of Donald Trump’s administration – but the fact they have become public.

The big questions being asked are: who leaked extracts from the ambassador’s communications and why? The memos are believed to have been distributed among as many as 100 senior politicians and civil servants in departments across Whitehall, making it difficult for the leak inquiry immediately to identify a source.