Princess Kate's sweet nickname for Prince Louis is going viral

The Wales family is undoubtedly the most talked-about in the world, making headlines for everything from their sweet family moments to their interactions with members of the public. 

This weekend was no exception as the nation celebrated the Coronation of King Charles III. And from the historic ceremony in Westminster Abbey and the Coronation Concert to the Bank Holiday Monday in celebration of volunteering, the Wales family was front and centre. 

Prince George's integral role in the Coronation ceremony and Princess Charlotte's huge curtsy to King Charles both made headlines. As did the viral photograph of the Wales family entering the Abbey, Prince William's sweet speech about the late Queen and Kate Middleton's iconic decision to wear a very millennial flower crown. 

In short, the Wales family were all anyone could talk about.

The most popular Wales family member over the Coronation weekend was undoubtedly little Prince Louis, from his hilarious facial expressions during the ceremony and his absence at the Coronation Concert to his personal landmark on the Monday - taking part in his first ever royal engagement.

Yes, the five-year-old completed his first ever royal engagement on the Bank Holiday,  joining the rest of his family at The Big Help Out with the Scouts.

Photographs from the event went viral, showing the miniature royal garden, ride a tractor with his dad and put his handprint on the wall. But the moments that got the world talking the most were the sweet interactions between the Prince and his mother.

In fact, it was during these interactions that Princess Kate accidentally let slip her lovely nickname for her youngest son - and it's very sweet.

As Prince Louis pushed a wheelbarrow, Princess Kate called out to him: "Well done! Good job, Lou bug!"

And later, when George, Charlotte and Louis were treated to a marshmallow toasting around a campfire, Kate used the nickname again.

"Pop that in the fire, Lou Bugs," Princess Kate was heard calling while instructing her youngest how to make S'mores. 

The miniature royal certainly looked very happy toasting marshmallows, with Prince William overheard telling the Scouts: "You've made his day."

Well, this is lovely.