Donald Trump acted like a "school boy on his best behaviour" when he reunited with the Queen earlier today, having arrived at Buckingham Palace for his first official state visit.
Body language expert Robin Kermode said the US president appeared not to want to put a foot wrong, having been widely criticised for walking in front of the Queen, 93, during the inspection of the guard at Windsor Castle on his last visit in July 2018.
Trump also appeared to "fist bump" the monarch as he went in for a handshake, with Her Majesty looking "genuinely pleased to see him again".
But while he was tentative with the Queen, the president greeted Prince Charles "like an old friend".
Speaking to the Daily Mail, Kermode said: "Mr Trump seems much more on his best behaviour this time than on his previous visit."
"In many of the pictures from Windsor Castle, he seemed to want to appear strong and determined, and even in some pictures wanting to take control. This time he appears more like a schoolboy not wanting to put a foot wrong."
Fellow body language expert Judi James said Trump, 72, was also "checking his choreography carefully" as he greeted members of the British royal family one by one.
"Trump did look more at home on this visit, although the way he and Melania did keep silently mouthing words suggested he was checking his own choreography carefully," James observed.
"His tendency to host and lead was still evident, with Charles needing to re-usher him with both arms when he tried to steer the prince, albeit with respect."
She added: "Donald Trump is more inhibited when he's shaking hands with the Queen. He was leaning forward from a distance, with a tentative pawing of her hand.
"The Queen only ever offers her fingertips so he couldn't get a grasp. He probably wasn't touching much more than her fingers."
As they chatted on the palace steps, Kermode noted how the Queen held her ground, facing Trump head on, while the president was left with a "slightly awkward leg position on the half turn".
"He would have been better doing a complete turn to face her rather than being caught in this half nowhere land of a stance," he said.
The president looked to be much more comfortable in the presence of the Prince of Wales, 70, greeting Charles "like an old friend".
James observed: "Trump pulled him in for a close-up handshake with his arm bent so their hands performed judders between their torsos, and even added a pat on the arm to imply high levels of friendship."
Likewise Charles, the consummate diplomat, "holds his head slightly lowered, giving respect to DT", Kermode points out.
"The prince's left shoulder, arm and hand is drawn away from Trump, showing some signs of formality and being on guard. His smile shows someone in control, in no way over-awed by the larger man."
James went on: "Trump chatted happily, with his gesticulation suggesting he was dominating the conversation, but with the two men's mirrored walks implying some rapport."
Kermode added: "The president usually tends to stride out slightly in front of other people, but with Charles he checks his pace out of respect. Though he does slip up when he abandons Charles to speak to the guard - who, I'm sure, is not supposed to respond!"
The Queen was all smiles as she welcomed the president and First Lady Melania to Buckingham Palace today, which James said suggested she was happy to host.
"Although his handshake with the Queen was odd enough to look like a fist bump, the Queen's wide grin made it appear she was genuinely pleased to see him again," she noted.
The Trumps are in the UK for a whirlwind tour which will see them dine with the royal family and commemorate the 75th anniversary of D-Day.