Richard Stonehouse - WPA Pool/Getty Images(LONDON) -- Happy birthday Prince William!
The royal dad of three and second-in-line to the British throne is celebrating his 37th birthday Friday.
William is celebrating his birthday privately but his royal family members sent birthday wishes publicly in a series of Instagram posts.
Clarence House, home to William's dad, Prince Charles, and his wife Camilla, the Duchess of Cornwall, shared an adorable throwback photo.
The pic shows William and Char..