Prince Philip, Queen Elizabeth’s 98-year-old husband, has spent a third night in a hospital while his wife and family gather at the Sandringham Estate in Norfolk, amid increasing speculation they may be forced to spend Christmas Day apart. The Queen attended a carol service on Sunday without Philip, who remains at the King Edward VII private hospital in central London, having traveled there Friday in what Buckingham Palace said was a “precautionary measure” for “observation and treatment” in connection with a pre-existing condition. The duke had cardiac stents inserted over Christmas 2011, when he was found to have a blocked coronary artery.