I used to enjoy the ghost stories of M.R. James, but I’ve never actually seen a ghost or even believed that ghosts existed. I have visited many allegedly haunted houses in my life but no scary apparition has ever crossed my path. The old house in which my grandparents lived in Lanarkshire was such a place (its ghost, like so many others around Britain, was supposed to be a ‘grey lady’), but I stayed there year after year untroubled by spirits, though the portraits of my puritan Scottish ancestors were sometimes frightening enough.