Prince Harry didn't hold hands with Meghan Markle in front of Queen Elizabeth II for a reason. Pictured: Markle, Prince Harry and Queen Elizabeth II at the Queen's Young Leaders Awards Ceremony at Buckingham Palace on June 26, 2018 in London. Getty Images/John Stillwell

Prince Harry declined to hold hands with Meghan Markle in front of Queen Elizabeth II for a reason.

Last week, the Duke and Duchess of Sussex joined the Queen at Buckingham Palace for the Queen's Young Leaders Awards. During the event, Markle was reportedly seen reaching out Prince Harry's for hand, but he ignored her efforts and instead brought his arms together.

According to People, Prince Harry "knows the drills when his grandmother, the Queen is around." On the other hand, Markle is still learning the ropes as a royal.

Queen Elizabeth II and Prince Philip have never showed PDA despite their closeness. In fact, they have never been seen holding hands in public. According to royal biographer Gyles Brandreth, this could be due to the "stoic values" of their generation.

Body language expert Robin Kermode also noticed how the Queen and the Duke of Edinburgh have kept themselves from touching each other in public. In fact, he believes that this set an unwritten protocol that the Duke and Duchess of Cambridge follow.

"The Queen rarely holds hands with her husband in public and this seems to have set an unwritten precedent for the other royals," Kermode said. "It is very clear that William and Kate are emotionally close, however, they do not seem to feel the need to prove their love – particularly when on official state business."

Meanwhile, a royal etiquette expert believes that this is a personal choice. The Queen and Prince Philip never hold hands in public, but Prince William and Kate Middleton sometimes do. Meanwhile, Prince Charles and Camilla Parker Bowles tend to hold hands just like Prince Harry and Markle.

"It is rare to see royal couples holding hands on official outings," Myka Meier said. "While we are much less likely to see The Duke and Duchess holding hands in public, we often see Prince Charles and The Duchess of Cornwall holding hands – it's all simply a matter of preference for each couple and is also likely dependent on the nature of the event they are attending. A more serious engagement would warrant a more serious level of professionalism, which each royal is sure to follow."