See More Adorable Pics of Prince George

Prince George just got another big first: his first British stamp!

In honor of Queen Elizabeth's 90th birthday, the tiny tot posed for a special portrait with his great grandmother, his grandfather, Prince Charles, and his father, Prince William. Each of their faces will be turned into a separate stamp.

In the photo, the 2-year-old steals the spotlight from his family members as he sports a white shirt, blue shorts, knee socks and a big grin. He's even standing on top of a stack of books to get close to his dad.

Can you believe how big he's gotten?!

Photographer Ranald Mackechnie, who kept the shoot secret from everyone (including his wife!), says Prince George was a pleasure to work with.

"He was absolutely charming, as you can see from the picture," Mackechnie tells The Telegraph. "You only have a short window of opportunity with small children, but Prince George was on good form and everyone seemed to enjoy seeing him enjoy the day."

"He was fascinated by my lights and all the kit, and he was quite happy standing on the blocks," he adds. "I took maybe 80 or 100 shots, but when I saw this one I knew straight away that was it."

Can't get enough of George? Click through the gallery above to see ALL of his adorable photos.