Robert became prominent because he acquired immense wealth by hismarriage. He took to wife Sibilla, daughter and heiress of Robert deEwyas, Lord Ewyas of Harold Ewyas in Hertfordshire, and in 9th of RichardI, had a suit with Herminus de Braton for the advowson of Braton churchin Norfolk, part of her vast inheritance. But it appears, though dulymarried, a strange contest arose in the 11th of King John regarding her;when William de Newmarket was summoned to show by what right he claimedto wife her who was Robert Tregoze's wife; for it appears that Richard Ihad given her to Tregoze in marriage. Whereupon Newmarket came and saidthat he had married her in the time of Richard I by gift of Robert deEwyas, her father. It is very certain, however, that Tregoze hadsufficient power to retain the heiress, for in 14 of King John theyrecovered lands in Somerset, in the right of Sibella. Meanwhile SirRobert de Tregoze was High Sheriff of Wiltshire, 3rd of Richard I, and inthree years afterwards was engaged in the expedition made into Normady.In first of John 1200 he gave the King 200 marks in silver to havegranted to him the wardship of the heir and lands of Geoffrey Hose, andin the 7th of John, 1206, on collecting scutage of that King's reign,answered 38 marks for 19 knight's fees, belonging to the honour of Robertde Ewyas, his father-in-law. He died about 1212. Sibilla, his wife,survived him and married 2nd Roger de Clifford and died 1236. They hadtwo sons, daughter.