Kate Middleton’s signature sign of affection to Prince William has been captured in a photo.

The Duke and Duchess of Cambridge are very modest when it comes to packing on public display of affection. They are very different from Prince Harry and Meghan Markle who are often photographed holding each other’s hand or touching each other even while on royal duties.

However, even if Prince William and Middleton are very reserved, there are rare cases when they couldn’t help but touch each other and some of those moments were caught on camera.

A photo of Middleton placing a hand on Prince William’s lap has resurfaced on Instagram. The photo was taken during the Duke and Duchess of Cambridge’s royal wedding. According to a netizen, the gesture is the duchess “signature sign of affection” to Prince William whenever they are in public.

“We have Kate do this in one of our animated emojis! It's like her signature sign of affection to William in public! She puts her hand on his leg & then hearts fly!!” the royal fan commented on the post.

In 2017, Middleton made the same gesture when she and Prince William appeared on BBC’s “Blue Peter.” During their interview, Middleton touched Prince William’s knees as they playfully joked around. At the time, Middleton and Prince William were still expecting their third child, Prince Louis.

The couple also has another way to pack on PDA. Prince William and Middleton do not hold hands but touch each other’s back to subtly show each other their affection. By doing this, they can still make each other feel their presence but the act is not as attention grabbing as holding hands because their hands are placed on each other’s back.

Many netizens also praised Prince William and Middleton for choosing the best time when to hold hands. A clip of the family was shared on Twitter where Prince William and Middleton were seen locking fingers. It happened while they were enjoying their vacation and not during a public engagement.

“Aww. Look at them holding hands! They know the correct time and place for that!! Not during official engagements!” one commented.

Prince William and Kate Middleton
Prince William and Kate Middleton journey by carriage procession to Buckingham Palace following their marriage at Westminster Abbey on April 29, 2011 in London. Getty Images/Sean Gallup