Sir Thomas Grey, Kt., of Werke and Heaton

Thomas Grey (1384–1415)

Sir Thomas Grey (30 November 1384 – 2 August 1415), of Castle Heaton near Norham,[1] Northumberland, was one of the three conspirators in the Southampton Plot against King Henry V in 1415.

Sir Thomas Grey, born 30 November 1384 in 'le Midyllgathouse’ at Alnwick Castle,[2] seat of the Percys, Earls of Northumberland, came from a family long prominent among the gentry in the border region of Northumberland.[3]

He was the eldest son and heir of Sir Thomas Grey (1359 - 26 November 1400) of Heaton near Norham, Northumberland, by his wife, Joan Mowbray (d.1410), sister of Thomas de Mowbray, 1st Duke of Norfolk,[4] and daughter of John de Mowbray, 4th Baron Mowbray (d. 17 June 1368), and Elizabeth de Segrave, daughter and heiress of John de Segrave, 4th Baron Segrave. Through his mother, a granddaughter of Margaret, Duchess of Norfolk (d.1399), Sir Thomas Grey was a descendant of King Edward I. His paternal grandparents were the soldier and chronicler Sir Thomas Grey (d. 1369) of Heaton, and Margaret, daughter and heiress of William de Presfen (or Pressen).[5]

He had three brothers and a sister:[6]

• John Grey, 1st Earl of Tankerville (d.1421), who married Joan de Cherleton, stepsister of Edmund Mortimer, 5th Earl of March.[7]
• Sir Henry Grey of Ketteringham, Norfolk, who married Emme Appleyard.[8]
• William Grey, Bishop of Lincoln (d.1436).[9]
• Maud Grey (1382–1451), who married Sir Robert Ogle (d. 12 August 1436) of Ogle, Northumberland, by whom she had issue.[10]

Grey's father, Sir Thomas Grey (1359-1400), and Sir Thomas Erpingham, were among those chosen to witness the abdication of King Richard II on 29 September 1399.[11]

Grey was only 16 years of age when he succeeded his father in 1400, and was shown great favour in the early years of the reign of Henry IV, including the grant of the wardship of his own inheritance while he was under age.[11] By August 1404 he had been retained for life by Ralph Neville, 1st Earl of Westmorland, but by May 1408 was in the service of Henry, Prince of Wales.[11]

Grey's part in the Southampton Plot was attributed by Grey himself to 'poverty and covetousness'.[12] In 1412 Grey married his 12-year-old son and heir, Thomas Grey, to Isabel, the 3-year-old daughter of Richard of Conisburgh, 3rd Earl of Cambridge. As part of the marriage settlement, Grey acquired the lordship of Wark-in-Tyndale at a 'bargain price', which was nonetheless more than he could afford, leading Pugh to conclude that Grey was Cambridge's 'dupe', 'whose intrigues brought them both to disaster'.[13]

Grey, Cambridge, and Henry Scrope, 3rd Baron Scrope of Masham, were the ringleaders of the Southampton Plot of 1415, which tried to assassinate King Henry V at Southampton before he sailed to France and to replace him with Edmund Mortimer, 5th Earl of March.[14] On 31 July 1415 Mortimer revealed the plot to the King at Portchester Castle, near Portsmouth.[15] The conspirators were promptly arrested and executed. Sir Thomas Grey was beheaded at the North Gate of Southampton on 2 August 1415.[16]

The Southampton Plot is dramatized in Shakespeare's Henry V, and in the anonymous play, The History of Sir John Oldcastle.

Sir Thomas Grey married, before 20 February 1408, Alice Neville, the daughter of Ralph Neville, 1st Earl of Westmorland, by his first wife Margaret (d.1396), daughter of Hugh de Stafford, 2nd Earl of Stafford, by whom he had four sons and four or five daughters:[17]

• Sir Thomas Grey (1404 – d. before 1426), who in 1412, at eight years of age, was betrothed to Isabel, then three years of age, only daughter of Richard of Conisburgh, 3rd Earl of Cambridge,[18] and Anne Mortimer, they had one son.[19]
• Sir Ralph Grey (d. 17 March 1442), who married Elizabeth FitzHugh, daughter of Henry FitzHugh, 3rd Baron FitzHugh, and Elizabeth Grey, and left issue.[20]
• Sir John Grey.[21]
• William Grey (d.1478), Chancellor of Oxford University, Bishop of Ely, and Lord High Treasurer.[22]
• Eleanor who married Sir John Arundel.[23]>
• Joan Grey, who married Sir John Salvin.[21]
• Elizabeth Grey, who married firstly, Sir William Whitchester, and secondly, Sir Roger Widdrington.[21]
• Margaret Grey, who married Gerard Widdrington.[citation needed]

Grey's widow, Alice, married Sir Gilbert Lancaster, by whom she had one son, Sir Gilbert Lancaster. Alice was still living on 22 August 1453.[21]

From: https://en.wikipedia.org/wiki/Thomas_Grey_(1384%E2%80%931415)

__________________

• Sir Thomas Grey, Sheriff of Northumberland, Constable of Bamburgh1,2,3,4,5,6,7
• M, #12973, b. 30 November 1384, d. 3 August 1415
• Father Sir Thomas Grey, Constable of Norham, Steward, Sheriff, Escheator, & Chief Justice of the episcopal liberty of Norhamshire & Islandshire, Earl Marshal8,9,10 b. c 1359, d. 26 Nov 1400 or 3 Dec 1400
• Mother Joan Mowbray8,9,10 b. c 1363, d. a 8 Jun 1407
• Sir Thomas Grey, Sheriff of Northumberland, Constable of Bamburgh was born on 30 November 1384 at Alnwick Castle, Yorkshire, England..2,3,6 He married Alice Neville, daughter of Sir Ralph Neville, 1st Earl Westmoreland, 4th Baron Neville and Margaret Stafford, before 20 February 1408; They had 4 sons (Sir Thomas; Sir Ralph; Sir John, & William, Bishop of Ely, Lord High Treasurer) and 4 or 5 daughters (including ((unnamed), wife of (Mr.) Arundel); Joan, wife of Sir John Salvin; & Elizabeth, wife of Sir William Whitchester, & of Sir Roger Widdrington).2,11,3,4,5,6,7 Sir Thomas Grey, Sheriff of Northumberland, Constable of Bamburgh died on 3 August 1415 at North Gate, Southampton, Hampshire, England, at age 30; Beheaded for taking part in the conspiracy of Richard, Earl of Cambridge against King Henry V.2,3,6
• Family Alice Neville d. a 22 Aug 1453
• Children
  • Joan Grey+ d. 1488
  • Elizabeth Grey+12 b. c 1402, d. 12 Jul 1454
  • Sir Thomas Grey13,14,15,5 b. c 1404, d. b 25 Apr 1426
  • Sir Ralph Grey, Warden of Roxburgh Castle+2,3,6 b. 9 Sep 1406, d. 17 Mar 1443
  • William Grey, Lord High Treasurer, Bishop of Ely, King's Proctor at the Roman Curia, Papal Protonotary & Referendary16 b. c 1410, d. 4 Aug 1478
• Citations
• [S3690] Unknown author, Magna Charta Sureties, 1215, 4th Ed., by F. L. Weis, p. 71; Plantagenet Ancestry of 17th Century Colonists, by David Faris, p. 117; Wallop Family, p. 253.
• [S5] Douglas Richardson, Plantagenet Ancestry, p. 354.
• [S16] Douglas Richardson, Magna Carta Ancestry, 2nd Edition, Vol. II, p. 257.
• [S16] Douglas Richardson, Magna Carta Ancestry, 2nd Edition, Vol. III, p. 248.
• [S16] Douglas Richardson, Magna Carta Ancestry, 2nd Edition, Vol. IV, p. 401-402.
• [S4] Douglas Richardson, Royal Ancestry, Vol. III, p. 108-109.
• [S4] Douglas Richardson, Royal Ancestry, Vol. IV, p. 236.
• [S5] Douglas Richardson, Plantagenet Ancestry, p. 353-354.
• [S16] Douglas Richardson, Magna Carta Ancestry, 2nd Edition, Vol. II, p. 254-255.
• [S4] Douglas Richardson, Royal Ancestry, Vol. III, p. 106-107.
• [S5] Douglas Richardson, Plantagenet Ancestry, p. 540-544.
• [S61] Unknown author, Family Group Sheets, Family History Archives, SLC.
• [S11583] The Wallop Family and Their Ancestry, by Vernon James Watney, p., p. 387.
• [S11568] The Complete Peerage of England, Scotland, Ireland, Great Britain, and the United Kingdom, by George Edward Cokayne, Vol. V, p. 138.
• [S5] Douglas Richardson, Plantagenet Ancestry, p. 793-794.
• [S4] Douglas Richardson, Royal Ancestry, Vol. III, p. 109.
• From: http://our-royal-titled-noble-and-commoner-ancestors.com/p432.htm#i... _________________
• Sir Thomas Grey1
• M, #14505, b. 30 November 1384, d. 3 August 1415
• Last Edited=8 Aug 2008
• Sir Thomas Grey was born on 30 November 1384 at Alnwick Castle, Northumberland, England.2 He was the son of Sir Thomas Grey and Joan de Mowbray.3 He married Lady Alice Neville, daughter of Ralph de Neville, 1st Earl of Westmorland and Lady Margaret de Stafford, before 1402.1 He died on 3 August 1415 at age 30 at North Gate, Southampton, Hampshire, England, beheaded.2
• He lived at Heton, County Durham, England.1
• Children of Sir Thomas Grey and Lady Alice Neville
  • Sir Thomas Grey b. c 1402, d. b 26 Jul 1443
  • Sir Ralph Grey+4 b. 9 Sep 1406, d. 17 Mar 1443
• Citations
• [S8] BP1999 volume 1, page 15. See link for full details for this source. Hereinafter cited as. [S8]
• [S125] Richard Glanville-Brown, online <e-mail address>, Richard Glanville-Brown (RR 2, Milton, Ontario, Canada), downloaded 17 August 2005.
• [S37] BP2003 volume 2, page 1660. See link for full details for this source. Hereinafter cited as. [S37]
• [S37] BP2003. [S37]
• From: http://www.thepeerage.com/p1451.htm#i14505 _________________
• Thomas GREY of Heton (Sir Knight)
• Born: 30 Nov 1384, Castle Alnwick, Northumberland, England
• Died: 3 Aug 1415, North Gate, Southampton, Hampshire, England
• Notes: Beheaded.
• Father: Thomas GREY (Sir Knight)
• Mother: Joan MOWBRAY
• Married: Alice NEVILLE ABT 1401
• Children:
  • 1. Elizabeth GREY
  • 2. Thomas GREY (Sir Knight)
  • 3. Ralph GREY (Sir Knight)
  • 4. Joan GREY
  • 5. Dau. GREY
  • 6. William GREY
  • 7. Margaret GREY
  • 8. John GREY
• From: http://www.tudorplace.com.ar/GREY8.htm#Thomas GREY of Heton (Sir Knight)1 ______________

Sir Thomas Grey of Heaton (Alnwick Castle, November 30, 1384– August 5, 1415, Southampton), was the son of Sir Thomas Grey of Heaton and Joan Mowbray. Born at Alnwick Castle, seat of the Percy Earls of Northumberland, he came from an old military family of the North Country.

What part, if any, he played in the Percy revolt of 1405 is not clear. However, he became a ringleader of the Southampton Plot in 1415, which aimed to murder King Henry V in Southampton before he sailed to France, and replace him with Edmund Mortimer, 5th Earl of March. However, Mortimer revealed the plot to the King, and the conspirators were promptly arrested and executed.

He married Alice Neville, daughter of Ralph Neville, 1st Earl of Westmoreland, by whom he had eight children:

• 1. Elizabeth Grey (c. 1402–1454), married Sir Roger Widdrington
• 2. Sir Thomas Grey (c. 1405–1443), without issue
• 3. Sir Ralph Grey (1406–1443), married Elizabeth Fitzhugh and left issue
• 4. Joan Grey (c. 1408–1488), married Sir John Salvine
• 5. a daughter (b. c. 1410), married an Arundell
• 6. William Grey
• 7. Margaret Grey (b. c. 1414), married Gerard Widdrington
• 8. John Grey

____________________

From the English Wikipedia page on the Southampton Plot:

http://en.wikipedia.org/wiki/Southampton_Plot

The Southampton Plot of 1415 was a conspiracy against King Henry V of England, aimed at replacing him with Edmund Mortimer, 5th Earl of March.[1]

The three alleged ringleaders were

• Richard of Conisburgh, 3rd Earl of Cambridge, Mortimer's brother-in-law;
• Henry Scrope, 3rd Baron Scrope of Masham (whose uncle Richard le Scrope had been executed for his part in a 1405 revolt also supporting Mortimer's right); and
• Sir Thomas Grey of Heton.

They were charged with plotting to murder Henry at Southampton before his embarkation into France; revolts in favour of Mortimer by Lollards under Sir John Oldcastle in the West Country, and by the Percies in the North, would follow.

The nominal principal, the Earl of March, informed King Henry of the plot on July 31, claiming that he had only just become aware of it. Richard, Scrope, and Grey were promptly arrested. The trial took place in Southampton, on the site now occupied by the Red Lion pub.

Grey was put to death on August 3 and the two peers on August 5, both in front of the Bargate. The executions were carried out according to class: Richard, Earl of Cambridge, and Henry, Lord Scrope of Masham, were beheaded; Sir Thomas Grey, a commoner, was drawn and quartered.

Satisfied, Henry sailed for France on August 11.

This plot features prominently in William Shakespeare's play Henry V. With the death of the Duke of York, the Earl of Cambridge's elder brother, at the Battle of Agincourt later that year, Cambridge's son Richard Plantagenet became heir to the title, which would eventually be returned to him after Henry V's death. Through his mother, he also inherited the Mortimer claim to the throne on the Earl of March's death; later in life Richard would use this claim to try to dethrone King Henry VI.

Notes

1.^ Mortimer was the great-grandson of Lionel of Antwerp, 1st Duke of Clarence, the third son of King Edward III. Henry V and his father Henry IV derived their claim from Henry IV's father John of Gaunt, 1st Duke of Lancaster, fourth son of Edward III. By strict primogeniture, Mortimer had a greater claim to the throne than King Henry, and his father had been acknowledged heir to the throne by King Richard II.

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• Links
• https://en.wikipedia.org/wiki/Ralph_Neville,_1st_Earl_of_Westmorland
• https://en.wikipedia.org/wiki/Isabel_of_Cambridge,_Countess_of_Essex
• https://en.wikipedia.org/wiki/William_Grey_(bishop_of_Ely) ______________

  ---

• Per genealogist notation in WikiTree profile: This Elizabeth Grey WIDDRINGTON was the daughter of Thomas Grey (1384-1415) one of three conspirators in the Southampton Plot against King Henry V.
• The recorded cause of death for Thomas Grey as recorded in Biographical Summaries of Notable People. Cause of death: Hanged, drawn, and quartered - August 2 1415 Citation under 'Sources'.
• Following narrative taken from: https://en.wikipedia.org/wiki/Thomas_Grey_(1384%E2%80%931415)

[Redaction mine, jlphawn 10/24/15]

Thomas Grey (1384–1415)

Sir Thomas Grey

Spouse(s) Alice Neville

Issue

• Sir Thomas Grey
• Sir Ralph Grey
• Sir John Grey
• William Grey
• daughter whose first name is unknown
• Joan Grey
• Elizabeth Grey
• Margaret Grey

Father: Sir Thomas Grey

Mother: Joan Mowbray

• Born 30 November 1384 Alnwick Castle, Northumberland
• Died 2 August 1415 (aged 30) Southampton
• Sir Thomas Grey (30 November 1384 – 2 August 1415), of Castle Heaton near Norham, Northumberland, was one of the three conspirators in the Southampton Plot against King Henry V in 1415.

Family

• Sir Thomas Grey, born 30 November 1384 in 'le Midyllgathouse’ at Alnwick Castle, seat of the Percys, Earls of Northumberland, came from a family long prominent among the gentry in the border region of Northumberland.
• He was the eldest son and heir of Sir Thomas Grey (1359 - 26 November 1400) of Heaton near Norham, Northumberland, by his wife, Joan Mowbray (d.1410), sister of Thomas de Mowbray, 1st Duke of Norfolk, and daughter of John de Mowbray, 4th Baron Mowbray (d. 17 June 1368), and Elizabeth de Segrave, daughter and heiress of John de Segrave, 4th Baron Segrave.
• Through his mother, a granddaughter of Margaret, Duchess of Norfolk (d.1399), Sir Thomas Grey was a descendant of King Edward I.
• His paternal grandparents were the soldier and chronicler Sir Thomas Grey (d. 1369) of Heaton, and Margaret, daughter and heiress of William de Presfen (or Pressen)

He had three brothers and a sister:

• John Grey, 1st Earl of Tankerville (d.1421), who married Joan de Cherleton, stepsister of Edmund Mortimer, 5th Earl of March.
• Sir Henry Grey of Ketteringham, Norfolk, who married Emme Appleyard.
• William Grey, Bishop of Lincoln (d.1436).
• Maud or 'Matilda' Grey (1382–1451), who married Sir Robert Ogle (d. 12 August 1436) of Ogle, Northumberland, by whom she had issue.

Career

• Grey's father, Sir Thomas Grey (1359-1400), and Sir Thomas Erpingham, were among those chosen to witness the abdication of King Richard II on 29 September 1399.
• Grey was only 16 years of age when he succeeded his father in 1400, and was shown great favour in the early years of the reign of Henry IV, including the grant of the wardship of his own inheritance while he was under age.
• By August 1404 he had been retained for life by Ralph Neville, 1st Earl of Westmorland, but by May 1408 was in the service of Henry, Prince of Wales.
• Grey's part in the Southampton Plot was attributed by Grey himself to 'poverty and covetousness'.
• In 1412 Grey married his 12-year-old son and heir, Thomas Grey, to Isabel, the 3-year-old daughter of Richard of Conisburgh, 3rd Earl of Cambridge.
• As part of the marriage settlement, Grey acquired the lordship of Wark-in-Tyndale at a 'bargain price', which was nonetheless more than he could afford, leading Pugh to conclude that Grey was Cambridge's 'dupe', 'whose intrigues brought them both to disaster'.
• Grey, Cambridge, and Henry Scrope, 3rd Baron Scrope of Masham, were the ringleaders of the failed Southampton Plot of 1415, which was a plot to assassinate King Henry V at Southampton before he sailed to France, and to replace him with Edmund Mortimer, 5th Earl of March.
• On 31 July 1415 Mortimer revealed the plot to the King at Portchester Castle, near Portsmouth.
• The conspirators were promptly arrested and executed. Sir Thomas Grey was beheaded at the North Gate of Southampton on 2 August 1415.
• The Southampton Plot is dramatized in Shakespeare's Henry V, and in the anonymous play, The History of Sir John Oldcastle.
• Sir Thomas Grey married, before 20 February 1408, Alice Neville, the daughter of Ralph Neville, 1st Earl of Westmorland, by his first wife Margaret (d.1396), daughter of Hugh de Stafford, 2nd Earl of Stafford, by whom he had four sons and four or five daughters:
• Sir Thomas Grey (1404 – d. before 1426), who in 1412, at eight years of age, was betrothed to Isabel, then three years of age, only daughter of Richard of Conisburgh, 3rd Earl of Cambridge,[18] and Anne Mortimer, they had one son.
• Sir Ralph Grey (d. 17 March 1442), who married Elizabeth FitzHugh, daughter of Henry FitzHugh, 3rd Baron FitzHugh, and Elizabeth Grey, and left issue.
• Sir John Grey.
• William Grey (d.1478), Chancellor of Oxford University, Bishop of Ely, and Lord High Treasurer.
• Eleanor who married Sir John Arundel.
• Joan Grey, who married Sir John Salvin.
• Elizabeth Grey, who married firstly, Sir William Whitchester, and secondly, Sir Roger Widdrington.
• Margaret Grey, who married Gerard Widdrington.
• Grey's widow, Alice, married Sir Gilbert Lancaster, by whom she had one son, Sir Gilbert Lancaster. Alice was still living on 22 August 1453.

Footnotes

• Pugh 1988, p. 1.
• King 2005, p. 69;
• Richardson II 2011, p. 254;
• Pugh 1988, p. 108.
• Pugh 1988, p. 102.
• King 2004, p. 69.
• Richardson II 2011, p. 254;
• Richardson III 2011, p. 206;
• Pugh 1988, pp. 103, 187, 196.
• Richardson II 2011, p. 254;
• Pugh 1988, p. 187.
• Richardson I 2011, p. 428;
• Pugh 1988, pp. 104, 187.
• Richardson II 2011, pp. 254–6.
• Pugh 1988, p. 187.
• Richardson II 2011, pp. 257, 390.
• Pugh 1988, p. 103.
• Pugh & 1988 pp.103, 161.
• Pugh 1988, p. 104.

The historian Pugh contents that "there was no plot in 1415 to assassinate Henry V and his three brothers and that heinous charge, by far the most sensational in the indictment, was fabricated to ensure that Cambridge, Gray and Scrope did not escape the death penalty as a well-deserved punishment for the various other offences that they undoubtedly had committed". Pugh 1988, p. xii.

• Pugh 1988, p. 116.
• Pugh 1988, p. 122;
• Richardson II 2011, p. 257.
• Richardson II 2011, p. 257;
• Pugh 1988, p. 103.
• Pugh 1988, pp. 104, 187.
• Burke's Peerage & Baronetage, 106th Edition, Charles Mosley Editor-in-Chief, 1999 Page: 15, 1222
• Richardson II 2011, pp. 257–8;
• Pugh 1988, p. 187.
• Richardson II 2011, p. 257.
• Richardson II 2011, p. 257;
• Pugh 1988, p. 187.
• The Visitations of the County of Cornwall, 'Arundell of Lanherne,' with additions by Lieutenant-Colonel J. L. Vivian, Exeter: William Pollard & Co. 1887 pp. 2-5

References

• Haines, Roy Martin (2009). Gray, William (c.1388–1436). Dictionary of National Biography. Retrieved 14 October 2012. (subscription required)
• Haines, Roy Martin (2004). Grey , William (c.1414–1478). Dictionary of National Biography. Retrieved 14 October 2012.
• King, Andy (2005). "Scaling the Ladder: The Rise and Rise of the Grays of Heaton, c.1296-c.1415". In Liddy, *Christian D. North-east England in the Later Middle Ages. Woodbridge: Boydell Press. pp. 57–74.
• Pugh, T.B. (1988). Henry V and the Southampton Plot of 1415. Alan Sutton. ISBN 0-86299-541-8
• Richardson, Douglas (2011). Magna Carta Ancestry: A Study in Colonial and Medieval Families, ed. Kimball G. Everingham I (2nd ed.). Salt Lake City. ISBN 1449966373
• Richardson, Douglas (2011). Magna Carta Ancestry: A Study in Colonial and Medieval Families, ed. Kimball G. Everingham II (2nd ed.). Salt Lake City. ISBN 1449966381
• Richardson, Douglas (2011). Magna Carta Ancestry: A Study in Colonial and Medieval Families, ed. Kimball G. Everingham III (2nd ed.). Salt Lake City. ISBN 144996639X
• Tout, Thomas Frederick (1885–90). Mortimer, Edmund de (1391-1425) 39. Dictionary of National Biography, 1885-1890. pp. 123–5. Retrieved 2 October 2012.

Further reading

• Barker, Juliet (2006). Agincourt: The King, the Campaign, the Battle. United Kingdom: Abacus. ISBN 978-0-349-11918-2.
• Curry, Anne (2005). Agincourt: A New History. United Kingdom: Tempus Publishing. ISBN 978-0-7524-2828-4.
• Mortimer, Ian (2009). 1415: Henry V's Year of Glory. London: The Bodley Head. ISBN 978-0-224-07992-1.
• Mosley, Charles (ed.), (1999). Burke's Peerage and Baronetage, 106th edition, 2 volumes (Crans, Switzerland: Burke's Peerage (Genealogical Books) Ltd, 1999), volume 1, p. 15.
• Mosley, Charles (ed.), (2003). Burke's Peerage, Baronetage & Knightage, 107th edition, 3 volumes (Wilmington, Delaware, U.S.A.: Burke's Peerage (Genealogical Books) Ltd, 2003), volume 2, pp. 1660–1661.

Sir Thomas Grey Knekt av Werke og Heaton

• 1384 Han var eldste sønn og arving til slottet Heaton, Norham Northumberland
• ca. 1401 Thomas og Alice gifter seg, De fikk 8 barn
• 1414 Det ble avtalt ekteskap mellom hans eldste sønn Thomas Grey 12 år og Isobel 3 år, datter av Richard av Conisburgh, 3 jarl av Cambridge. Som del av ekteskaps utligningen kjøpte Grey Wark-in-Tyndale til en røverpris. Dette var likevel mer enn han hadde råd, noe som førte til at Pugh å konkluderte med at Grey var den mest lettlurte i Cambridge "Hvis intriger førte dem begge til katastrofe".
• 1415 Sir Thomas Grey av Heaton var en av tre som konspirerte mot kong Henry V "Southampton Plot" De andre var Richard Earl Cambridge og Henry Lord Scrope av Masham . Sammensvergelsen handlet om makten til tronen. Den er noen ganger referert til som Cambridge handlingen. Edmund Mortimer avslørte komplottet til kongen på Portchester Castle, nær Portsmouth. den 31. mars 1415. Konspiratørene ble straks arrestert og henrettet. Sir Thomas Grey ble halshugget ved nord porten i Southampton den 2. august 1415.

Greys del i "Southampton Plot" ble beskrevet av Grey selv som "fattigdom og begjær".