Weis' "Ancestral Roots", (54:33), states he was Justice of Chester and custodian of Chester Castle. His parents are not given. Also mentioned (70:33). Cokayne's "Complete Peerage" (Badlesmere, pp. 371-372), does not speculate as to the identity of his parents.
From a posting to the soc.genealogy.medieval newsgroup on Internet by Homer B James on 22 Dec 1995: Known first as a great rebel to King Henry III., for which he was excommunicated by the Archbishop of Canterbury; but, subsequently, returning to his allegiance, as Justice of Chester, in that office he continued until the 9th year of King Edward I. (1280-1281). In the next year he was in the expedition made into Wales, and in the 25th year of the same monarch, in that into Gascony, having previously, by the writ of January 26 in that year, been summoned to the parliament at Salisbury for the following Sunday, the feast of St. Matthew, September 21, as Gunselm de Badlesmere. He died four years afterwards, seized of the manor of Badlesmere, which he held in capite of the crown, as of the barony of Crevequer, by the service of one knight's fee. He married _______ Bernard, the heiress of Ralph Bernard, Lord of Kingsdowne, and was succeeded by his son, then twenty-six years of age, Bartholomew.