Gerard was the nephew of Walkelin , Bishop of Winchester , and Simon , Abbot of Ely . His parents was Osbert and Anna , and his brother Peter was also a royal clerk . Where he was born and raised is unknown ; he is documented as cantor of Rouen Cathedral , and precentor of the same cathedral , although the date of his appointment to either office is unrecorded . By 1091 he had become archdeacon of Rouen . He served in the royal chancery under successive kings of England , William I and William II .