US president Joe Biden and his wife Jill are currently gearing up for their Sunday tea sit down with the Queen during a trip to the UK for the G7 summit.
But it appears the American leaders might have already breached apparent royal protocol early on, after reportedly arriving at one of the first official events, the Eden Project reception on Friday, after the Queen.
The Queen and other members of the royal family are hosting the world leaders during the summit, and according to the experts, protocol varies depending on the occasion.
For example, at a state event, like a banquet, guests are seated before the Queen enters the room.
A guide of Regal do's and don'ts published by the BBC suggests guests should arrive before the Queen.
However, on some occasions she is seen welcoming the guests, greeting them one by one, which of course means she would be there first.
Marlene Koenig, royal historian, explained to Bazaar.com in 2019: "When it is a formal event, a state dinner, attending the ballet (sitting in the royal box), a reception, a wedding, the royals are the last to arrive."
"At state dinners, all of the guests are in their seats before the royals arrive.
"The Queen enters first followed by other royals. She will walk with the head of state."
Etiquette guide Debrett's confirms this, adding: "It is correct for everyone to arrive before the royal personage and protocol rules that no guest should leave an event before a member of the royal family."
Is the Queen really bothered by breaches of protocol?
However, any apparent faux pas is likely to have been ignored by the Queen, who is not actually overly concerned by protocol.
Joe Little, managing editor of Majesty magazine told Yahoo UK: "The Queen, steeped in tradition after almost 70 years on the throne, has a very keen eye and will immediately notice that something is not as it should be.
"However, she fully appreciates that things do occasionally go wrong, but would never admonish her guests and make them feel uncomfortable. That's not her style."
It's the Biden's first time meeting the Queen this week, although they have met both her son Prince Charles and her grandson Prince Harry.
Ahead of the meeting, Jill said she and her husband were looking forward to meeting the Queen
"That’s an exciting part of the visit for us. We’ve looked forward to this for weeks and now it’s finally here. It’s a beautiful beginning," she said.
She was asked after her meeting with the Duchess of Cambridge if she had sought advice for meeting the Queen from Kate.
But she replied: "No I didn't. We've been busy. Were you not in that room? We were talking education."
The couple will go to Windsor Castle on Sunday afternoon for tea with the monarch. Biden will inspect a Guard of Honour before the trio goes for a private meeting.
Biden's predecessor Donald Trump made plenty of headlines during his visits to the UK as US President, with a series of gaffes and royal protocol breaches himself.
There was that time he walked in front of the Queen instead of behind her, or his awkward handshake-fist pump combo when greeting her at the palace.
Or who could forget the moment he broke the rules and physically touched the Queen during a white tie state banquet at Buckingham Palace in 2019.
Royal fans lose it over Queen cutting the cake with a sword
At an earlier engagement the Queen was with her daughter-in-law the Duchess of Cornwall and granddaughter-in-law Duchess of Cambridge at the Eden Project in Cornwall, to celebrate the Big Lunch.
When it came time to cut the cake, the Queen was given a ceremonial sword by Edward Bolitho, the Lord-Lieutenant of Cornwall, though shed doubt on the idea of using it, saying: "I don't think it's going to work."
She was told: "There is a more conventional knife available" but Her Majesty quipped back: "I know there is, this is more unusual."
Camilla, 73, came to her aid, helping her with the unwieldy weapon, and the two women successful sliced the whole way through.
Royal fans went wild when footage of the hilarious moment hit social media.
"She is a treasure!" one person said on Twitter. "I love it when old ladies just decide they're gonna do something weird and then do it."
"The Queen does it her way. The big smile on Kate's face just makes it perfect," another mused.
While a third wrote: "She's the Queen. If she wants to cut a cake with a sword, who are we to stop her?"
Additional reporting by Rebecca Taylor.
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