Prince George dresses in traditional wear so his clothes don't date in photos.
Children's wear designer Rachel Riley believes Prince William and Duchess Catherine opted to purchase some of her Riley's clothing for their three-year-old son because the items she sells are timeless and well suited to "formal occasion wear".
She said: "While I don't wish to mimic period drama [shorts are wider and longer, proportions more relevant for the 21st century], I do think my clothes are traditional and that is perhaps the appeal for the Duchess of Cambridge.
"My clothes are better suited for formal occasion wear, which is predominantly what people come to us for. They're not going to date in photos in years to come."
While Rachel couldn't confirm what George and his sister Princess Charlotte, 16 months, will wear for their forthcoming royal engagement in Canada next week, she is expecting William and Catherine, who are both 34, to have purchased some patriotic attire for their kids.
She added to the Daily Telegraph newspaper: "It's an official engagement and they are representing their country so I imagine something red, white and blue might feature."
The designer also admitted royal fans could see the pair in some more casual attire in the north American country.
She said: "But Canada is also known as the great outdoors so I'm sure there will definitely be some casual pieces, too."
The eight-day visit will be Charlotte's first overseas engagement.
William, Catherine, George and Charlotte will head to Canada on Saturday (24.09.16), where they will first visit Victoria.