“Willielmus comes de Ferrariis” donated property to Tutbury Priory, for the soul of “uxoris meæ Sibillæ et liberorum meorum”, by charter which names “antecessores mei…Henricus de Ferrariis et Engenulphus et Robertus avus meus et Robertus comes pater meus”.
He succeeded his father [before 1160) as Earl [of Derby]. “Robertus [mistake for Willielmus] comes de Ferrariis” donated property to Dore Abbey, for the souls of “Sibilla de Braosa, uxoris meæ matris W. filii mei et sua, et…Bertæ (fuit filia Milonis comitis Herefordiæ) matris uxoris meæ”, by undated charter. He participated in the Third Crusade and died during the siege of Acre.
The Annals of Margan record the death in 1190 of “Willelmus comes Ferrariis”. Matthew Paris records the death at Acre in 1191 of "comes de Ferariis". A letter dated 21 Oct 1190, recording the arrival of the archbishop of Canterbury at Tyre, names “...comes de Ferreres...” among those who had died [in Palestine]. 1
WILLIAM [DE FERRIERES], EARL OF DERBY, or EARL OF FERRIERES, son and heir. He was one of the adherents of the younger Henry on his rebellion in April 1173, and sacked and burnt Nottingham in May or June 1174. He made his submission to the King at Northampton, 31 July 1174, surrendering his castles of Tutbury and Duffield (c). The King took him, with other prisoners, to France in August following, and imprisoned them at Caen.
He married Sibyl, daughter of William de Braiose, Lord of Bramber, by Bertha (heiress of Brecon and Over Gwent), sister and coheir of William DE HEREFORD, and 2nd daughter of Miles (DE GLOUCESTER), EARL OF HEREFORD (e). He died on Crusade, at the siege of Acre, in palestine, in 1190, before 21 October. His wife survived him, and married 2ndly Adam de Port, Lord of Basing, who died 1213, and was, perhaps, living as late as 5 February 1227/8.
(c) Tutbury Castle was one of those which the King caused to be demolished in Dec 1175.
(e) "Robertus (sic) Comes de Ferrieres. . . . The mistake of writing 'Robertus'--instead of 'Willelmus'--in this transcript has been the principal source of error in the various pedigrees of the Earls of Derby that have been put forward. For mistake it must be. In what may be called the official account 'de farsifacte Willelmi de Boasa (son of the William mentioned in the text) in 1208, it is twice mentioned that 'W. Comes de Ferariis was nepos suus.' And the Earl is one of the witnesses to the truth of the document. Now it is perfectly certain that the Earl of Ferrieres living in 1208 was son of a William, and not of a Robert. It appears, however, that this whole charter is a fabication by Vincent. Apart from giving the wrong name to the Earl, the charter is nearly identical to one of Robert de Stafford for Bordersley Abbey. This charter being the sole evidence for the marriage of Earl William, it now does not appear whom he did marry. 2
William de Ferrers, 3rd Earl of Derby, rebelled against Henry II and marching at the head of the Leicestershire men (19th Henry II) upon Nottingham, then kept for the king by Reginald de Luci, got possession of the town which he sacked, putting the greater part of the inhabitants to the sword and taking the rest prisoners. He was soon afterwards, however, reduced to submission and obliged to surrender to the crown his castles in Tutbury and Duffield, which were demolished by order of the king. His lordship m. Sibilla, dau. of William de Braose, Lord of Abergavenny and Brecknock, by whom he had issue. 3