Donald Trump has grown frustrated with Theresa May’s “school mistress” tone, allies of the president have told The Telegraph, as it emerged the pair will not hold formal talks at the G7 summit in Canada.

The US president is said to bristle at the Prime Minister’s approach during phone calls, with Mrs May quick to get into policy details rather than wider conversation.

One senior US diplomat said Mr Trump had expressed annoyance at Mrs May’s frequent demands, which are seen as taking advantage of the UK-US relationship.

Another long-time friend of the president revealed he had privately complained of how Mrs May calls him out in public when he is deemed to have stepped out of line.

A third figure, a former White House official who attended meetings between the pair, confirmed the frosty relationship: "No offence, but she is basically a school mistress. I’m not sure anyone gets on well with her.”