William Hercy was the son of Thomas de Hercy and Elizabeth; and he was the grandson of John de Hercy and Joanna. He was the g-grandson of Hugo/Hugh de Hercy and Alicia. The latter was the sheriff of Nottinghamshire and Derbyshire during the reign of King Edward III.
https://media.geni.com/p13/23/52/47/a3/5344484caebf5be8/hercy_pedig...
https://en.wikipedia.org/wiki/Sheriff_of_Nottinghamshire,_Derbyshir...
