The late baroness allegedly had a complex relationship with her granddaughter.Ruth Roche, Lady Fermoy—Princess Diana's maternal grandmother—at her home circa 1982.Credit: Tim Graham Photo Library via Getty ImagesThe GistPrincess Diana’s maternal grandmother Ruth Roche, Lady Fermoy, was a longtime lady-in-waiting to Elizabeth the Queen Mother.Lady Fermoy advised Diana against marrying Prince Charles due to their differing “sense of humor” and “li…