Robert de Ferrers, 4th Baron Ferrers of Chartley
Robert de Ferrers, 4th Baron Ferrers of Chartley( 1358 – 1413) was the son of John de Ferrers, 3rd Baron Ferrers of Chartley and Elizabeth de Stafford, a daughter of Ralph de Stafford, 1st Earl of Stafford and Margaret de Audley.
He inherited the title of Baron Ferrers of Chartley upon his father's death at the Battle of Nájera on 3 April 1367 but was never summoned to parliament.
Robert married Margaret Le Despenser( born around 1360) a daughter of Edward le Despencer, 1st Baron le Despencer, KG, and Lady Elizabeth Burghersh.
The couple had one son Edmund, who became Edmund de Ferrers, 5th Baron Ferrers of Chartley upon the death of his father around 1412, and one daughter Philippe, who married Sir Thomas Greene, Sheriff of Northamptonshire( 10 February 1399 – 18 January 1462), by whom she was the grandmother of Sir Thomas Green.
Philippe and Sir Thomas are ancestors to Queen consort Catherine Parr, the last wife of King Henry VIII.
Robert de Ferrers, 4th Baron Ferrers of Chartley died sometime around 1413 and is buried at Merevale Abbey in Warwickshire.
William de Warenne, 2nd Earl of Surrey
William de Warenne, 2nd Earl of Surrey( died 11 May 1138) was the son of William de Warenne, 1st Earl of Surrey and his first wife Gundred.
He was more often referred to as" Earl Warenne" or" Earl of Warenne" than as Earl of Surrey.
William de Ferrers, 3rd Earl of Derby
William I de Ferrers, 3rd Earl of Derby (died 1190) was a 12th-century English Earl who resided in Tutbury Castle in Staffordshire and was head of a family which controlled a large part of Derbyshire known as Duffield Frith.
He was also a Knight Templar.
William was the son of Robert de Ferrers, 2nd Earl of Derby, and his wife, Margaret Peverel.
He succeeded his father as Earl of Derby in 1162.
He was married to Sybil, the daughter of William de Braose, 3rd Lord of Bramber, and Bertha of Hereford.
William de Grey
William de Grey( 21 October
1652- 27 February 1687) of Merton Hall, Norfolk was an East Anglian landowner and Tory Member of Parliament.
He was the grandfather of his namesake William de Grey, 1st Baron Walsingham.
Robert de Ferrers, 6th Earl of Derby
Robert de Ferrers, 6th Earl of Derby( 1239 – 1279) was an English nobleman.
He was born at Tutbury Castle in Staffordshire, England, the son of William de Ferrers, 5th Earl of Derby, by his second wife Margaret de Quincy( born 1218), a daughter of Roger de Quincy, 2nd Earl of Winchester and Helen of Galloway.
Juliana de Vesci
Juliana de Vesci was the daughter of William de Vesci and Agnes Ferrers, daughter of William de Ferrers, 5th Earl of Derby.
Juliana de Vesci married Sir Richard de Vernon, son of Sir Richard de Vernon and Margaret de Vipont.
Robert de Ferrers, 2nd Earl of Derby
Robert II de Ferrers, 2nd Earl of Derby( c. 1100 – 1162) was a younger, but eldest surviving son of Robert de Ferrers, 1st Earl of Derby and his wife Hawise.
He succeeded his father as Earl of Derby in 1139( William, his elder brother, having been murdered in London some time before).
He was head of a family which controlled a large part of Derbyshire including an area later known as Duffield Frith.
John de Ferrers, 3rd Baron Ferrers of Chartley
John de Ferrers, 3rd Baron Ferrers of Chartley( c. 1331 – 3 April 1367) was the son of Robert de Ferrers, 2nd Baron Ferrers of Chartley and a woman named Margaret.
John de Ferrers was born in Southhoe, Huntingdonshire.
He inherited the title of Baron Ferrers of Chartley upon his father's death in 1350 but was never summoned to parliament.
Despite his youth, John fought in Gascony for Edward III in 1345 and married Elizabeth de Stafford( 1342 – 7 August 1375)- widow of Fulk le Strange( Baron Strange) and daughter of Ralph Stafford, 1st Earl of Stafford and Margaret de Audley, a daughter of Hugh de Audley, 1st Earl of Gloucester.
The couple had one son Robert, who became Robert de Ferrers, 4th Baron Ferrers of Chartley upon the death of his father in 1367.
John de Ferrers, 3rd Baron Ferrers of Chartley died on 3 April 1367 at the Battle of Nájera in Castile.
Ralph Neville, 3rd Earl of Westmorland
Ralph Neville, 3rd Earl of Westmorland( c. 1456 – 6 February 1499) was an English peer.
He was the grandfather of Ralph Neville, 4th Earl of Westmorland.
William de Ferrers, 4th Earl of Derby
William II de Ferrers, 4th Earl of Derby (c. 1168 – c. 1247), was a favourite of King John of England.
He succeeded to the estate (but not the title) upon the death of his father, William de Ferrers, 3rd Earl of Derby, at the Siege of Acre in 1190.
He was head of a family which controlled a large part of Derbyshire which included an area known as Duffield Frith.

Question: Who is the paternal grandfather of William De Ferrers, 4Th Earl Of Derby?
Answer: Robert de Ferrers, 2nd Earl of Derby