There was a protocol mistake at Kate and William's wedding you might never have noticed - involving the Queen

It's been thirteen years since Prince William and Kate Middleton married at Westminster Abbey - and there was one moment of the day that seemingly failed to follow royal protocol.

For the Prince and Princess of Wales's anniversary, we have been reflecting on the historic occasion and the details that have stayed etched in our memories such as Carole Middletons outfit the night before the wedding outfit and William’s romantic but risky proposal to Catherine .

The royal wedding, which took place on April 29th 2011, was an international spectacle watched by over 162 million viewers, that required months of meticulous planning. However, an etiquette expert has now noticed one significant error in royal protocol that occurred when the late Queen Elizabeth II arrived at the service.

Speaking to Hello! , Alexandra Messervy explained, "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."

"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," she added.

It was a rare, but major oversight in royal protocol as the Queen is usually let out curbside as historically, when royals were escorted by carriages and horses, gentlemen would get out into the road, while women would be on the pavement to avoid the mud.

"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," Alexandra continued.

"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."

However, even after the mishap, the Queen resolved the issue swiftly to make sure that she exited the car on the right side, by moving across and exiting the car from the same door as her husband.

"Thankfully, the Queen ignored the guard who opened her car door and instead scooted across to follow Prince Phillip out his curbside door."