Prince William and Duchess Catherine's youngest child turns four on Saturday (April 23) and on the eve of his birthday, the couple shared some sweet pictures of Louis dressed casually and playing on a Norfolk beach.
They posted the pictures on Twitter with the caption '4 years old tomorrow!' and added that the pictures were taken by Duchess Catherine, who is a keen amateur photographer.
Meanwhile, Louis is set to join his older siblings Prince George, eight, and Princess Charlotte, six, at a new school this September.
George and Charlotte currently attend Thomas's in Battersea, south-west London but Catherine and William are reportedly considering a move to Berkshire and have been looking at homes and schools.
A source told the Daily Mail newspaper that all three children will be leaving their London schools and the royal couple, in particular, love the idea of their family growing up not far from Catherine's own childhood home.
Said the source: "They are both country people at heart and Kate spends so much time with her family anyway. It makes perfect sense for them to all be at the same school together. If all three children are at school in Berkshire together, it also means George wouldn't have to board.
"The talk is that if they don't find a suitable place with the Queen at Windsor, they are likely to end up if not necessarily right next to [Catherine's parents in] Bucklebury, not far off it. They have been discreetly viewing potential properties in recent months."