William and Kate Mark Prince George's 13th Birthday With a Rare Home Video

Prince George turned 13 on Wednesday, and his parents marked it twice. The morning brought the expected birthday portrait, taken by Matt Porteous, with the prince in formal clothes. The afternoon brought something the Waleses almost never release.

The second post was a video, shot outdoors, of George and his younger brother Prince Louis simply being outside. It is unguarded in a way royal footage very rarely is, and it went up with a one line caption thanking everyone for the birthday wishes.

Eton in September

The birthday lands two months after Kensington Palace confirmed George will start at Eton College in September, following his father and his uncle to the school. A source close to the family told People at the time that George had always wanted to follow in his father's footsteps.

He has been appearing in public more often this year. He and Princess Charlotte joined their parents at Wimbledon for the men's singles final earlier this month, one of a handful of engagements he has attended since turning 12.

What is actually known about him

Very little, by design. William and Catherine have worked hard to keep the children's lives ordinary, and the result is that public knowledge of the future king runs to a few sentences. People reported last month that friends and observers describe him as thoughtful and serious.

The most revealing detail this year came from his mother. Visiting the Christie NHS Foundation Trust in Manchester in June, she stopped in a music therapy room and was asked what her children listen to. George, she said, wants more rock. He loves AC/DC. He plays the guitar.

It is a small thing to know about a boy who will one day be head of state, and for now that appears to be the entire point.