Revealed: the 'real' reason why Donald Trump and Theresa May held hands - and it's not what you think

But Government sources in Washington DC were suggesting that the hand-holding was not as a result of a deep and lasting friendship after all.

The insider said that Mr Trump is known to have an aversion to slopes or stairs, and said this could have been the reason for the president's decision to grasp the Prime Minister’s hand.

Such a fear is a recognised condition - called bathmophobia.

As the pair walked along the White House colonnade on Friday, they encountered the top of a gentle slope. It was Mr Trump who then offered his hand to Mrs May, apparently anxious the prime minister should steady the nerves of the world’s most powerful man.

The video footage of Mr Trump and Mrs May walking along the colonnade backs up the claim that the president made the first move.

Just as the couple reach the top of the slope, the president stretches out his left arm and grabs at Mrs May’s right hand. They then walk for about five steps before Mr Trump slides his left arm across and pats the underside of Mrs May’s hand, possibly grateful for her steadying presence.

The 'handgate’ row threatened to become a distraction to an event that until then had gone better than some might have hoped.

Lunch had been a cordial affair. Following on from a press conference that had witnessed the president in genial mood, the two leaders and their teams of delegates withdrew to the White House’s state dining room for what was described as a 'working lunch’.

Feasting on a first course of  'baby iceberg wedge’ salad with blue cheese, followed by braised beef short ribs with potato puree and glazed winter vegetables and a dessert of salted caramel creme brulee, talk quickly turned to Brexit before touching on the special relationship enjoyed by Ronald Reagan and Margaret Thatcher.

Present at the lunch were Mr Trump’s and Mrs May’s closest advisers befitting of the importance of the occasion.

Trump’s camp included his son-in-law Jared Kushner and his hugely controversial chief strategist Stephen Bannon, the executive chairman of the far-right website Breitbart News who has been accused of “fanning the flames of white supremacism”.

The vice president Mike Pence and Trump’s chief of staff Reince Priebus were also in attendance as well as Gary Cohn and Lt Gen Michael Flynn, the president’s chief economic and national security advisers. Hope Hicks, the glamorous director of strategic communications, was also at the lunch.

On May’s side, she brought her two most trusted and loyal aides Nick Timothy and Fiona Hill, her joint chiefs of staff; Sir Kim Darroch, our man in Washington, and Sir Mark Lyall Grant, national security adviser.

If Brexit dominated much of the conversation, Nigel Farage’s name was allowed to crop up only once. Perhaps Mr Trump was being sensitive to his hosts.

A source said: “They spoke a lot about Brexit. Trump was keen to hear the Prime Minister’s opinion about what had happened. He said he had already heard Nigel Farage’s position on Brexit and what had happened.”

They then spoke about their “shared admiration” for Mrs Thatcher. “Trump said that he had always looked up to Reagan and that he wants the relationship between him and May to be even better,” said the source.

At the end of the lunch, Trump took the menu card and handed it to an aide. Apparently, he likes to retain mementos over such occasions.

“Keep that safe,” he said, “I just had lunch with the British Prime Minister.”