Many observers have commented on how Melania Trump can come across as somewhat reserved. A smile from America’s First Lady is as rare as it is welcome and there are innumerable viral videos of Melania batting her husband’s hand away as he reaches out for a moment of human contact.

But King Charles, who it must be noted has been trained for a life of diplomacy almost since birth, managed to melt the Slovenian former model’s icy exterior. He was rewarded for his charm offensive with “a gentle touch on the sleeve, so lingering it would make royal protocol enthusiasts blench,” says royal biographer Christopher Wilson in the Telegraph.

He says it was a complete breach of the rules of royal protocol that underlined how successful his visit had been.

Against a background of very real tension between Britain and the United States, driven by the increasingly reckless outbursts of US president Donald Trump, His Majesty the King had been dispatched to reaffirm the so-called “special relationship” between the two countries.

The visit has been an undeniable smash hit. It has been “further evidence that the power of kingship goes beyond gilded carriages and palace balconies, and can be successfully applied in times of national need,” Christopher says.

King Charles not only successfully defrosted the notorious chilly First Lady, but won over President Trump too: “The King was rewarded with a smile and a Trumpian pat on the knee. Trump, in short, was on his best behaviour.”

Not only royalists, but republican experts too have praised King Charles’s stateside performance. Alastair Campbell, “lifelong” republican who has consistently championed the idea of replacing the British monarchy with an elected head of state, posted: “Excellent speech by King Charles… Loved the confidence in British and European values.”

Emily Maitlis, who famously precipitated one of the biggest crises in royal history when she interviewed Prince Andrew (as he was then called) for Newsnight, also praised the King’s performance. She said on her Newsagents podcast: “You send somebody out there and everyone applauds him and he carries it off. He did a sort of Love Actually speech, but written by Plato. That’s what it felt like, someone who lifted us all up a bit.”

The King’s visit was received just as well by American experts too. Republican senator Lindsey Graham, praised the King’s speech to Congress, saying: “Simply put: The King nailed it.”

“The speech was a terrific combo of wit, humor, history and appreciation. I believe most members of Congress feel better after the speech than they did before.”

Another Republican, Nikki Haley, former US ambassador to the UN, posted: “Amazing to see King Charles unify Congress in a way America craves.”

President Trump, notorious for creating division with every other word, was impressed by the way King Charles brought people together: “He got the Democrats to stand, I’ve never been able to do that. I couldn’t believe it,” Trump said at the banquet a few hours later. “They liked him more than they’ve ever liked any Republican or Democrat, actually.”

The King is only the third British sovereign to have visited the US, preceded only by his mother, Elizabeth II, and grandfather, George VI, who met with President Franklin D. Roosevelt a few months before the outbreak of World War 2.