The etiquette expert William Hanson said: “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.
“And no self-respecting aristo or royal would want to be considered suburban. Even the Duchess of Cambridge.”
The tradition can be traced back throughout the Royal Family, with Princes William and Harry also seen regularly wearing shorts until they were deemed old enough to progress to full-length trousers.