3 today! The Duke and Duchess of Cambridge have shared a new picture of Prince Louis

Not a baby anymore!

Prince Louis, the youngest child of the Duke and Duchess of Cambridge, is turning three today – and that is not the only milestone happening for this little royal this week. Following in the footsteps of his big sister, Princess Charlotte, little Louis started at Willcocks Nursery School in Kensington this week. And to mark both occasions,  proud mum Kate – who has become a bit of a royal photographer of late – snapped this gorgeous picture of her little boy – who is growing up so fast! The adorable image was taken at Kensington Palace on Wednesday by Kate, shortly before Louis left for his first day at nursery.

"Three tomorrow!" the Duke and Duchess wrote.

"Taken earlier this week by The Duchess before he left for his first day of nursery, The Duke and Duchess are pleased to share a new image of Prince Louis."

In the photo, little Louis grins while riding a red bicycle. He is seen wearing blue shorts, a navy sweater, and a blue and white collared shirt.

It also looks like the little prince is indeed headed to school, as he is carrying a blue backpack. The youngest Cambridge also looks ready to play in lime green and blue sneakers with crew socks.

Handy for the Cambridges, Willcocks Nursery School is just a short drive from their London home in Apartment 1A at Kensington Palace.