From the researches of Mr Nicolas, it appears that this eminent Baron was the eldest son of Nicholas Baron Segrave; and at his father’s death, in the 23d Edward I., was thirty-nine years of age. In the 54th Henry III., he married Christian, daughter of Hugh de Plessets, knight, and at the same time, his sister Amabil became the wife of his brother-in-law, Sir John de Plessets. Soon after the accession of Edward I., he was engaged in the wars of Scotland, and in the 13th Edward I. he attended the King in his expedition into Wales. In the 19th Edward I. he was with his father in the Scottish wars; and in the 24th Edward I. executed the office of Constable of the English army. Dugdale asserts, that in the 25th Edward I., John de Segrave was, by indenture, retained to serve Roger le Bigot, Earl of Norfolk, the Earl Marshal, with six knights, including himself, as well in peace as war, for the term of his whole life, in England, Wales, and Scotland, with the following retinue:--In time of peace, with six horses, so long as the Earl should think fit, taking _bouche of court_ for himself and six knights; and for his esquires hay and oats, together with livery for six more horses, and wages for six grooms and their horses. He was also to receive two robes for himself, as for a banneret, yearly, as well in peace as in war, with the same robes for each of his five knights, and two robes annually for his other bachelors. In war, he was bound to bring with him his five knights and twenty horses, in consideration of which, he was to receive for himself and his company, with all the said horses, xl s. per diem; but if he should bring no more than six horses, then xxij s. per diem. It was further agreed, that the horses should be valued, in order that proper allowance might be made, in case any of them should happen to be lost in the service; and, for the performance of this agreement, he had a grant from the Earl of the manor of Lodene in Norfolk.