Prince George is growing up so fast!

The royal family released a new portrait of Queen Elizabeth, Prince Charles, Prince William and little George — four generations of heirs to the British monarchy! — on Wednesday, April 20. The new photo was recently taken for a stamp sheet created to mark the Queen's upcoming 90th birthday.

prince george getty images

Charles, Elizabeth, George and William.

In the group snapshot, George, 2, looks adorable standing on a pile of foam blocks next to his 33-year-old father while holding onto William's hand. The image — featuring the foursome all clad in coordinating blue outfits! — was reportedly taken in summer 2015 at Buckingham Palace.

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William and his wife, Kate Middleton, welcomed son George in July 2013. The couple — who married in April 2011 — are also parents to an 11-month-old daughter, Princess Charlotte.