LONDON -- Prince William and his wife Kate have published two new photographs of their youngest son Louis to mark his fifth birthday on Sunday.

The photographs of Louis were taken by Millie Pilkington earlier this month in Windsor. In one, he is seen being pushed in a wheelbarrow by his mother, while the second is a close-up of a smiling Louis looking off to the side of the camera.

Louis is a grandson of King Charles and is fourth in line to the throne, behind his father William and siblings George and Charlotte.

Reporting by Kylie MacLellan; editing by Jonathan Oatis