Over the years I noted that Granny took an unusual interest in William Mason, especially since his father was not a tenant of Downton Abbey until recently. He was one of only two people she tried to get a medical exemption from the draft. She pulled all possible strings to make certain he died at Downton. She also pulled strings to make certain that he and Daisy could get married. I always wondered if William was Robert's half brother due to an affair between Robert's father and William's mother. If I remember, Mr and Mrs. Mason lost all there earlier children (possibly Rh factor) but William survived. William's mother wanted more for him than being a farmer; she urged him to go into service and aim to be a butler. Well, it was always a background thought for me. Perhaps Granny just liked young William more than the others. We do know that Granny and Roberts father did not have the best of marriages (ask the Prince) and as Granny noted they "were the Edwardians" Finally she admitted to Isobel at Christmas Season 5, that the Prince may not have been the only scandal in her life.