Britain's Prince William (L), Duke of Cambridge and his wife Catherine, Duchess of Cambridge attend a traditional Christmas Day Church Service at Sandringham in eastern England, on December 25, 2015. AFP PHOTO / BEN STANSALL / AFP / BEN STANSALL (Photo credit should read BEN STANSALL/AFP/Getty Images)

Britain's Prince William (L), Duke of Cambridge and his wife Catherine, Duchess of Cambridge attend a traditional Christmas Day Church Service at Sandringham in eastern England, on December 25, 2015.
AFP PHOTO / BEN STANSALL / AFP / BEN STANSALL        (Photo credit should read BEN STANSALL/AFP/Getty Images)