Mary Pershall, who writes under the pen name "Susan Shelley," is an author of over 20 novels, including a series of historical romances about the family of William Marshal:
- A Shield of Roses (1984) about Sir Richard fitzGilbert de Clare and Lady Eve MacMurrough, the parents of Isabel de Clare
- Dawn of the White Rose (1985) about William Marshal and Isabel de Clare, the parents of William fitzWilliam Marshal
- A Triumph of Roses (1986) about William fitzWilliam Marshal and Eleanor Plantagenet, daughter of King John and sister of King Henry III
- Roses of Glory (1987) about the fictional Giles, son of William fitzWilliam Marshal