Question: Who is the paternal grandfather of William De Ferrers, 4Th Earl Of Derby?

Knowledge 1: 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. [SEP] Knowledge 2: 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.
Knowledge 1: 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. [SEP] Knowledge 2: 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.
Knowledge 1: 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. [SEP] Knowledge 2: 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.

Answer: Robert de Ferrers, 2nd Earl of Derby