Prince Louis turns 3: How does he compare to other royals at the same age? 22 Apr, 2021 10:40 PM 7 minutes to read A cheeky Prince Louis is turning three tomorrow. Photo / Kensington Royal Daily Telegraph UK By: Harry Mount Prince Louis, the Cambridges' youngest son, turns 3 on Friday – St George's Day – and you can already begin to see his character emerging. He is the classic, cheeky, third-child scamp. It's the royal tradition to release a picture on a child's third birthday – part of the unwritten deal that, in return for official photographs, the paparazzi will leave the royal family alone. It helps, too, that the Duchess of Cambridge has become a considerable photographer in her own right, which means her subjects are at their most relaxed for her to capture these fun intimate portraits. The sort you only get from a little boy looking at his beloved mother, pleased as punch that he's mastered the crucial little boy's art of turning his bike handlebars – racing style.