George, who becomes a teenager today, is pictured casually posing on some stairs at Kensington Palace after Trooping the Colour last month.
The image was posted on the Instagram account of the Prince and Princess of Wales alongside the caption: “Happy 13th Birthday, George!”
It was taken by Matt Porteous, who’s previously taken other photos for the family.
Prince George is preparing to start at Eton College in September, the prestigious school near Windsor that also educated his father.
The second in line to the throne was previously at Lambrook School in Berkshire.
The prince was last seen with his parents and sister at Wimbledon a few weeks ago, with the family seen chatting to champion Jannik Sinner after the final.
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George’s birth drew the world’s media to the private wing of St Mary’s Hospital in Paddington, London.
His birth changed the order of succession, bumping Prince Harry down a place. His siblings, Charlotte and Louis, were born in 2015 and 2018.
