Royal events tend to undergo meticulous planning and execution, however, there have been plenty of occasions where mistakes have happened, with some almost going unnoticed.
In honour of Prince William and Kate's 13th wedding anniversary on Monday, we take a look back at one particular moment which almost went awry when the late Queen made her arrival. Watch the video below to see it unfold…
Upon her arrival, Queen Elizabeth II could be seen trying to tell her guardsman not to open her side of the car door in a blink-and-you-miss-it moment. The car had pulled up on the wrong side of the pavement at Westminster Abbey, leaving the Queen to slide over to the other side where Prince Philip had been sat.
Etiquette expert Alexandra Messervy noticed the faux pas immediately. "I spotted that the car conveying the Queen and the Duke of Edinburgh pulled up in entirely the wrong way in Dean's Yard at Westminster Abbey," she told HELLO!'s A Right Royal podcast hosts Andrea Caamano and Emmy Griffiths in an upcoming episode.
"The Queen got out on the wrong side and there was a bit of a fluster. I think the [guard] who opened the door appeared flustered when the Queen was actually not where she would normally be. The correct protocol for her was to be on the curbside, and she was on the reverse side.
"But looking back at it now since she never put her foot wrong - was it actually wrong? Did she perhaps have a sore leg that day and she couldn't let herself out on the left, was it easier to come on the right, I don't know."
"You always let the Queen out on the curbside," Alexandra said between sips of tea in the living room of her cosy cottage in Somerset, a rural county in southwest England. "Thankfully, the Queen ignored the guard who opened her car door and instead scooted across to follow Prince Phillip out his curbside door."
She added: "I think it was a faux pas and, of course, actually in any form of protocol, it is correct for the female to get out on the curbside. It's all because of the days of carriages and horses, the gentlemen enjoyed the outside of the pavement while the women were on the other to avoid the mud."
The Prince and Princess of Wales married in Westminster Abbey on 29 April 2011, and was watched by over 162 million viewers around the world.
The late Queen's arrival wasn't the only thing that may have raised eyebrows but not many people would have known that Princess Kate's bridal look broke a 350-year-old tradition, simply because she chose to wear her hair down.
According to the documentary, William & Kate: The Journey, Kate was encouraged by royal officials to wear her hair up, something she decided against.
"Royal sources tell me that the royals indicated very strongly to Kate that they would prefer her to wear her hair up for this very special occasion," said royal reporter Ashley Pearson.
It has been custom for royal brides throughout history to wear their hair up on their wedding day, and many brides even after the Duchess have adhered to this age-old convention.
Despite this, Kate's beautiful bridal choices will go down in royal history as one of the most iconic. Heir to the throne William married his former university flatmate Kate Middleton after an eight-year relationship.
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Over ten years on, the couple have three children, ten-year-old Prince George, Princess Charlotte, eight, and six-year-old Prince Louis.
Kate, in her role as a senior royal, has focused her charity work on early years, young people’s mental health, the visual arts and promoting the benefits of outdoor life.