Question: Who is the paternal grandfather of John Tuchet, 8Th Earl Of Castlehaven?

John Tuchet, 4th Baron Audley
John Tuchet, 4th Baron Audley, 1st Baron Tuchet (23 April 1371 – 19 December 1408) was an English peer.
John Tuchet, 4th Baron Audley was the son of Sir John Tuchet, called "Baron Audley", and his wife Maud, widow of Sir Richard de Willoughby.
His paternal grandparents were Sir John Tuchet (1327—1371) and his wife Joan Audley (1331–1393, daughter of James Audley, 2nd Baron Audley and first wife Lady Joan Mortimer).
In 1391, when his childless great-uncle Nicholas Audley, 3rd Baron Audley died, the Audley Barony was abeyant.
Meanwhile, he was created 1st Baron Tuchet in 1403 and received one-third of the share of the barony of Audley.
In 1408 the Barony was revived, and John Tuchet became 4th Baron Audley.
Before 1398, he married Elizabeth Stafford, daughter of Sir Humphrey Stafford and his first wife, Alice Grenville.
They had one son, James, and two daughters, Margaret and Elizabeth.
John was succeeded by his only son, James Tuchet.
Edward Talbot, 8th Earl of Shrewsbury
Edward Talbot, 8th Earl of Shrewsbury, 8th Earl of Waterford( christened 25 February 1561 – 8 February 1617), was the younger brother and nearest male heir of Gilbert Talbot, 7th Earl of Shrewsbury, whom he succeeded as Earl of Shrewsbury and Lord High Steward of Ireland in 1616.
James Tuchet, 3rd Earl of Castlehaven
James Tuchet, 3rd Earl of Castlehaven( c. 1617 – 11 October 1684) was the son of Mervyn Tuchet, 2nd Earl of Castlehaven and his first wife, Elizabeth Barnham( 1592 – c. 1622).
Castlehaven played a prominent role in the Wars of the Three Kingdoms that took place in the middle of the 17th century, and was particularly active in the conflicts in Ireland at this time.
John Tuchet, 8th Earl of Castlehaven
John Talbot Tuchet, 8th Earl of Castlehaven (2 August 1724 – 22 April 1777) was the son of James Tuchet, 6th Earl of Castlehaven, and his wife, née Elizabeth Arundell.
He succeeded his brother as Earl of Castlehaven and Baron Audley on 6 May 1769.
He died unmarried, at which time the Earldom of Castlehaven and two of its subsidiary titles (Baron Audley of Orier and Baron Audley of Hely) became extinct as the Irish earldom and baronies were entailed honours.
The Barony of Audley created by writ of 1312 is deemed to have devolved upon his nephew, namely George Thicknesse (later Thicknesse-Touchet).
George was the son of his sister Elizabeth, who had married Philip Thicknesse
James Tuchet, 7th Earl of Castlehaven
James Tuchet, 7th Earl of Castlehaven( 15 April 1723 – 6 May 1769) was the son of James Tuchet, 6th Earl of Castlehaven and his wife, née Elizabeth Arundell.
He succeeded his father as Earl of Castlehaven and Baron Audley on 12 October 1740.
He was unmarried, and succeeded on his death in 1769 by his brother, John.
He was a Christian Earl who owned much land and donated parts of the proceeds to the church.
John Tuchet, 8th Baron Audley
John Tuchet, 8th Baron Audley, 5th Baron Tuchet( c. 1483 – c. 1557) was an English peer.
Gilbert Talbot, 3rd Baron Talbot
Gilbert Talbot, 3rd Baron Talbot( c. 1332–1387) was an English nobleman and soldier.
He was the grandfather of John Talbot, 1st Earl of Shrewsbury.
James Tuchet, 5th Earl of Castlehaven
James Tuchet, 5th Earl of Castlehaven( died 12 August 1700) was the son of Mervyn Tuchet, 4th Earl of Castlehaven and Mary Talbot.
He succeeded his father as Earl of Castlehaven on 2 November 1686.
He married Anne Pelson, daughter of Richard Pelson and his wife, née Anne Villiers, daughter of Christopher Villiers, 1st Earl of Anglesey.
They had one son, James, who succeeded him as Earl of Castlehaven.
He died of apoplexy.
His gravestone is in the floor of the south aisle of the retrochoir at Winchester Cathedral.
James Tuchet, 6th Earl of Castlehaven
James Tuchet, 6th Earl of Castlehaven (died 12 October 1740) was the son of James Tuchet, 5th Earl of Castlehaven and his wife Anne Pelson.
He succeeded his father as Earl of Castlehaven and Baron Audley on 9 August 1700.
He married, on 14 May 1722, Elizabeth Arundell (1693–1743), daughter of Henry Arundell, 5th Baron Arundell of Wardour and his wife, née Elizabeth Panton.
They had two sons, and at least one daughter:
He is buried at the church of St. Sulpice in Paris, France.
Mervyn Tuchet, 4th Earl of Castlehaven
Mervyn Tuchet, 4th Earl of Castlehaven( died 2 November 1686) was the third son of Mervyn Tuchet, 2nd Earl of Castlehaven, and his first wife, Elizabeth Barnham( 1592 – c. 1622).
He married Mary Talbot( buried 15 March 1710/ 1), daughter of John Talbot, 10th Earl of Shrewsbury( bef. 1601 – 1654) and his wife, née Mary Fortesque.
They had at least three children:
He succeeded his brother James as Earl of Castlehaven on 11 October 1684.
He also held the lower titles 14th Baron Audley and 2nd Baron Audley of Hely.
On his death, his titles passed to his son James.

Answer: James Tuchet, 5th Earl of Castlehaven