Britain's Prince William, the Duke of Cambridge, and his wife Catherine, the Duchess of Cambridge, sit in the Royal Box on Centre Court before the start of the men's singles final match between Serbia's Novak Djokovic and Switzerland's Roger Federer on day thirteen of the 2014 Wimbledon Championships at The All England Tennis Club in Wimbledon, southwest London, on July 6, 2014. AFP PHOTO / CARL COURT  - RESTRICTED TO EDITORIAL USE        (Photo credit should read CARL COURT/AFP/Getty Images)