If there's one word that springs to mind when one hears "state visit," it's probably "protocol." Especially when it involves the House of Windsor, whose namesake castle is where King Charles III will host US President Donald Trump during his second state visit to the United Kingdom this week. Due to renovation work, the gilded halls of Buckingham Palace are off-limits this time.

Typically, US presidents serving a second term are not offered a state visit. Instead, they are invited for tea or lunch with the monarch.

With Trump becoming the first US president to be offered a second state visit, UK Prime Minister Keir Starmer has described the event as "truly historic" and "unprecedented."

Altogether, there have been less formal state visits from US presidents than one might think: During Queen Elizabeth II's reign from 1952 to 2022, only three such events were held — with George W. Bush, Barack Obama and Trump.

Carriage procession included

Trump — who earlier this year ruffled some American feathers for tweeting "Long live the King" in reference to himself — will be welcomed to Windsor by Prince William and Princess Catherine on Wednesday and treated to a royal carriage procession. This had been avoided on his previous state visit, as security logistics were deemed too complex for the event held in London.

According to Sky News, this week's itinerary includes a military parade, laying a wreath at Queen Elizabeth's tomb in St George's Chapel, a flypast by the Red Arrows and F-35 jets, a formal dinner and plenty of ceremonial flourishes. 

It's a schedule steeped in tradition, but behind the polished silver and ceremonial swords lies a minefield of royal protocol — an etiquette labyrinth where even seasoned statesmen have stumbled.

(In)famous protocol breaches by presidents — or their spouses

During his 2019 visit, Trump famously walked ahead of Queen Elizabeth, leaving the diminutive monarch momentarily obscured behind his hulking figure — a flub that launched countless headlines.

To be fair though, Trump, is hardly the first American leader to fumble the royal rule book.

His predecessor, Joe Biden — wearing his signature Ray-Ban aviator sunglasses — had etiquette experts tut-tutting when he greeted the queen in 2021.

"If you're meeting the queen face-to-face, there's no sunglasses or anything like that at all because eye contact is quite important with any introduction," Grant Harrold, who served as a royal butler to then-Prince Charles, told Newsweek.

Former first lady Michelle Obama once placed a friendly arm around the queen's shoulders in 2009, a gesture that warmed hearts but raised eyebrows.

She later explained in her memoir "Becoming," that the moment was born of sore feet and shared humanity: "Forget that she sometimes wore a diamond crown and that I'd flown to London on the presidential jet: We were just two tired ladies oppressed by our shoes. I then did what's instinctive to me anytime I feel connected to a new person, which is to express my feelings outwardly. I laid a hand affectionately across her shoulder."

She added that if her action was considered "improper" protocol-wise, "I had at least done the human thing."

Going further back to Washington's Camelot era, Jackie Kennedy's 1961 visit with President John F. Kennedy also apparently stirred royal waters. As dramatized in Netflix's "The Crown," her dazzling presence reportedly unsettled the queen, who felt upstaged by the first lady's glamour and intellect. The episode may have taken creative liberties, but it captured the tension that can arise when British ceremony meets American charisma.

Maintaining that stiff upper lip

Queen Elizabeth, who hosted every US president from Harry S. Truman to Biden (save for Lyndon B. Johnson), had the diplomacy game down pat. She maintained her poise and sense of humor over the years, from Bush's 2007 gaffe suggesting she'd visited the US in 1776 to riding horses with Ronald Reagan at Windsor in 1982.

It became part of her mystique: Whether it was a late arrival, an overzealous gesture or a conversational misfire, the queen rarely flinched. 

King Charles has now stepped into her shoes to continue this delicate dance of hosting world leaders. His style is more conversational, less inscrutable — but the stakes remain high.

Potential for meme-worthy moments

As with any high-profile meeting, every handshake, step, glance or even fashion choice will be scrutinized, dissected or memed.

And Trump, never one to shy from spectacle, could deliver — be it his signature "clasp and yank" handshake or a comment that veers off script.

Just this past July at a press conference in Scotland, the president took another swipe at London Mayor Sadiq Khan, calling him "a nasty person" who has "done a terrible job," leaving Prime Minister Starmer, who was seated beside him, momentarily gobsmacked. 

Protocol hiccups notwithstanding, state visits serve to strengthen ties and reaffirm alliances. To be clear, state visits are extended by the British monarch on the advice of the government.

Thus, given the geopolitical state of the world and Trump's potential to either fan or douse flames, British media have referred to this visit as a "royal charm offensive" and "a schmooze fest."

"It's not just about carriages and tiaras. It's about the world agenda," Lord Simon McDonald, former permanent under-secretary at the Foreign Office and head of the Diplomatic Service, told Sky News, referring to Trump's 2019 visit.

Yet, for the press and public, it's the pageantry — and the potential for missteps — that makes such visits tantalizing with the possibility of fodder for coverage, clicks and conversations.

Edited by: Elizabeth Grenier