THURSTAN DE MONTFORT, son and heir, was a minor when he succeeded his father in or before 1199. In 1205 the King took his homage and gave him his land on condition that he demised it for two years to William de Cauntelo. In the summer of 1206 he was abroad in the King's service. In 1210 he was serving the King in Ireland; and in 1214 he was excused the scutage of Poitou, because he fought himself. He appears to have joined in the rebellion against John, and in March 1215/6 had letters of safe conduct on coming to the King. The name of his wife is not known.(a) He died before 21 November, and possibly before 23 July, 1216. [Complete Peerage IX:122-3, (transcribed by Dave Utzinger)]
[a] It is possible that he married a daughter of William de Cauntelo the elder, steward of the household to King John. His son Piers wrote to Walter de Merton, Chancellor 1261-63, about the business of (Walter de Cauntelo) Lord (Bishop) of Worcester, avunculi nostri; and William de Cauntelo, brother of the bishop, was concerned with the minorities of both Thurstan and his heir. Thurstan left a younger son William, who had from his brother a life interest in property at Ringwood.
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Thurstan de Montfort, who had great law suits in King John's time with Eustace de Stutevill and Nicholas de Stutevill regarding a portion of the lordship of Cotingham, co. York, d. in 1216, and was s. by his son, Peter de Montfort. [Sir Bernard Burke, Dormant, Abeyant, Forfeited and Extinct Peerages, Burke's Peerage Ltd, London, England, 1883, p. 377, Montfort, Barons Montfort]