Prince William and Kate Middleton joined the rest of the royal family for their annual Christmas walk in Sandringham on Christmas day, and were accompanied by Prince William's step siblings, Laura Lopes (aka his "secret sister") and Tom Parker Bowles.
According to Hello! Magazine, Tom and Laura attended the Christmas day service at St Mary Magdalene Church, but "made a private arrival." Meaning they didn't show up in photos of the royals like this one:
FYI, William […]
Prince William's "Secret Sister" Joined the Royals for Christmas, But Made a "Private Arrival"