Richard Ledgett, deputy director of the NSA, told BBC News the idea that Britain had a hand in spying on Trump was “just crazy”.

“It belies a complete lack of understanding of how the relationship works between the intel community agencies, it completely ignores the political reality of ‘would the UK government agree to do that?'”, Ledgett said.

There would be no advantage for Britain’s government in spying on Trump, given the potential cost, he said.

“It would be epically stupid,” said Ledgett, who is due to retire shortly.