Caroline Rush, Queen Elizabeth II and Anna Wintour attend the Richard Quinn show during London Fashion Week. Photo / Getty Images
It's long been believed that when meeting the Queen or other members of the royal family there are strict rules to adhere to.
And while several experts have dismissed the existence of such protocols in the past, the biggest rule seems to be: don't touch His or Her Majesty, reports Metro UK - and only shake their hand if you are offered it.
Other rules include: don't expect the monarch to chat to you if you are sitting on her left during a meal. Don't leave an event before the King or Queen, don't turn your back on them, take photos, ask personal questions, or get "too over-excited".
And many of the rich and famous who have been lucky enough to meet the Queen, King Charles, and the Prince and Princess of Wales have often slipped up in their presence.
As per the British monarchy's official website, "there are no obligatory codes of behaviour when meeting a member of the Royal Family", but it adds, "Many people wish to observe the traditional forms". So, here are just a few of the celebrities who have committed a royal faux pas.
Sir Lewis Hamilton
Formula 1 star Lewis Hamilton was one who got "over-excited" at lunch with the Queen a year after he was presented with an MBE in 2009.
"I was excited and started to talk to her but she said, pointing to my left, "No, you speak that way first and I'll speak this way and then I'll come back to you'," he told the Graham Norton Show.
Fortunately for him, after about five minutes she did speak to him. "She is a sweet woman and we talked about how she spends her weekends, houses and music. She is really cool," he said at the time.
This one may be a close call rather than a faux pas, according to Buckingham Palace, but there's a reason a photo of NBA star LeBron James meeting the now-Prince and Princess of Wales went viral.
The snap shows him with his arm around Kate Middleton. But Buckingham Palace spokesperson Laura King said at the time: "The Duke and Duchess of Cambridge very much enjoyed their time in the US, including attending the NBA game and meeting LeBron.
"When members of the Royal Family meet people they want them to feel as comfortable as possible. There is no such thing as Royal protocol."
Ed Sheeran
Pop star Ed Sheeran touched the now-King Charles III's arm as he shook hands with him while being awarded his MBE at Buckingham Palace in 2017.
That's a no-no when it comes to meeting the royals.
Sheeran told NBC afterwards, "Apparently, I did a big faux pas, though. I shook his hand and then grabbed it, and you're not meant to do that."
Anna Wintour
While sitting front row at Fashion Week with the Queen, Vogue editor-in-chief Anna Wintour kept her sunglasses on while chatting with the monarch.
Royal etiquette expert later told the Press Association that failing to remove her shades was "unacceptable".
"She should have removed them before being in the presence of the Queen, let alone in discussion."
Geri Horner
Who could forget the infamous moment Geri Horner of the Spice Girls patted the bottom of the now King Charles III?
But the former Ginger Spice insists she didn't "pinch" him, as was reported at the time.
"I patted it," she told the Times. "Patting him on the bottom was against royal protocol but we're all human. It was the premiere of our film, Spice World, in the late 90s There was a lot of nervous energy – young women, happy antics."
Mickey Rooney
Actor Mickey Rooney dismissed the "no touching the Queen" rule when she visited the US in 2007.
Greeting her at a garden party in Washington, he took her gloved hand and kissed it - but the monarch didn't seem to mind.
Michelle Obama
Former First Lady Michelle Obama caused a stir in 2009 when she placed her arm around the Queen.
But despite the supposed "protocol", Her Majesty responded by placing her own arm around Michelle Obama.
She recalled in her memoir Becoming, "I 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."
It wasn't until after the meeting that she realised it would have been seen as an "epic faux pas", but she added, "If I hadn't done the proper thing at Buckingham Palace, I had at least done the human thing.
"I daresay the Queen was okay with it, too, because when I touched her, she only pulled closer, resting a gloved hand lightly on the small of my back."