You may have gotten an answer by now, but in all likelihood, this refers to William de Graham, who has been said to actually be William de Hesdin, son of Arnulf de Hesdin. Arnulf de Hesdin (Hesding), was born in 1038 in Pas-De-Calais, France and died after 1091.Arnulf was a Flemish nobleman, related to many of the royal and noble houses of Europe, and related to the Stewarts and speculatively, the Grahams.Although not named as a known companion of William, Arnulf de Hesdin was granted numerous holdings in England after the Conquest, according to the Domesday book. Arnulf married Aveline of France and is said to have had four children. Walter inherited the county of Hesdin from his uncle, while William crossed over to England at the time of the Norman Conquest with William I and Arnulf. The two daughters of Arnulf and Aveline, (Maud and Aveline) married into the Chaworth and FitzAlan families respectively. The FitzAlans who descended from Aveline became the Stewart kings.The Grahams and Royal Stewarts called each other cousin, and the Grahams intermarried with the Stewarts several times.