Prince William's 'secret' step-sister will be joining the Royal Family this Christmas - but their relationship hasn't always been so cosy. This year's annual festivities in Sandringham will reportedly include some 45 attendees - their largest festive gathering in some years. Prince William himself let the number slip during a festive gathering in Wiltshire for the families of the 1st Battalion Mercian Regiment, sharing: "We'll be in Norfolk, at Sandringham. We'll be 45 for Christmas. It won't