Parentage unsure according to ref 169. He held a knight's fee in Chilworth and Coombe in Great Milton, Oxfordshire in 1223 (these places have also been known as Chilworth Gernon and Coombe Gernon). He also held land in Lavington, Wiltshire. In 1216, William Briwere regained possession of that land from Matilda, then widow of William de Egewurth, and Briwere gave this land to Roger Gernon as part of a settlement relating to Gernon's marriage to Matilda. Matilda died before 1225 and in 1225 William Blund sued Briwere for hereditary rights to the land at Lavington, In 1226 Blund regained possession and Roger Gernon acknowledged him as overlord.