Under a strict royal rule, Prince Louis must wear shorts while attending public events while his brother Prince George can wear trousers.

The style choice stems from a time-honoured aristocratic dress code that will see the youngest son of the Prince and Princess of Wales wear shorts until he's eight years old.

At this year's Trooping the Colour, Louis was the picture of charm in his dark blue shorts, coordinated with a navy jacket and light blue tie.

The young royal matched his brother George and sister Princess Charlotte, who wore a sailor-style dress in the same hue as her brothers's suits.

The young prince seems quite content with his legwear choice despite the rainy conditions that proved to be a bit of a challenge for those participating in the parade this year.

William Hanson, an authority on etiquette, told Harper's Bazaar that it's customary for upper-crust families, including the royal household, to keep boys in shorts until they hit eight years old. At that point, they can switch to trousers.

Mr Hanson delved into the history for Harper's Bazaar, stating: "It's a very English thing to dress a young boy in shorts.

"Trousers are for older boys and men, whereas shorts on young boys is one of those silent class markers that we have in England."

"Although times are slowly changing, a pair of trousers on a young boy is considered quite middle class quite suburban."

He added: "And no self-respecting aristo or royal would want to be considered suburban."

Prince William and Prince Harry adhered to this tradition in their younger years, as did George until his eighth birthday in July 2021.

With Louis's eighth birthday not due until April 2026, he still has several years of shorts-wearing ahead.

The Princess of Wales did temporarily have Louis depart from the tradition over the Christmas period last year.

The young royal was seen wearing trousers as he attended his mother's Christmas carol concert in Westminster Abbey and then again for the traditional walkabout after mass on Christmas Day.