Question: Who is the paternal grandfather of Roger Grey, 1St Baron Grey Of Ruthin?

Knowledge 1: Roger Grey, 1st Baron Grey of Ruthin
Roger Grey, 1st Baron Grey of Ruthin (c. 1298 – 6 March 1353) was summoned to parliament in 1324.He saw much service as a soldier.Roger was the son of John Grey, 2nd Baron Grey de Wilton and Maud de Verdon.He married Elizabeth daughter of John Hastings, 1st Baron Hastings of Bergavenny, by whom he had a son who succeeded as Reginald Grey, 2nd Baron Grey de Ruthyn. [SEP] Knowledge 2: John Grey, 2nd Baron Grey de Wilton
John Grey, 2nd Baron Grey of Wilton (died 28 October 1323) was an English nobleman and administrator.He was the son of Reginald de Grey, 1st Baron Grey de Wilton and his wife Maud de Verdun (or Maud daughter and heir of William Baron FitzHugh).His first office was as vice-justice of Chester from 1296 to 1297.He participated in the siege and capture of Caerlaverock Castle in July 1300, and his arms were recorded in the "Roll of Caerlaverock", a roll of arms compiled during the diese.He was summoned to Parliament from 1309 to 1322.His first parliamentary appointment was that of Lord Ordainer in 1310, and was followed by the grant in 1311 of Ruthin Castle, which passed to his younger son Roger de Grey.He was at the Battle of Bannockburn, where the English army took a heavy defeat.Nonetheless he was trusted by Edward II who was confident in the appointment as Justice of North Wales in Feb 1314/15 and Governor of Caernarfon Castle.He was relieved of his constabulatory responsibilities the following year and called to raise troops in response to the insurrection led by Llywelyn Bren.He served as Conservator of the peace for Bedfordshire in 1320.In 1322, he was commanded to raise troops in Wales and join the royal muster at Coventry.
Knowledge 1: Roger Grey, 1st Baron Grey of Ruthin
Roger Grey, 1st Baron Grey of Ruthin (c. 1298 – 6 March 1353) was summoned to parliament in 1324.He saw much service as a soldier.Roger was the son of John Grey, 2nd Baron Grey de Wilton and Maud de Verdon.He married Elizabeth daughter of John Hastings, 1st Baron Hastings of Bergavenny, by whom he had a son who succeeded as Reginald Grey, 2nd Baron Grey de Ruthyn. [SEP] Knowledge 2: John de Grey, 2nd Baron Grey de Rotherfield
John de Grey, 2nd Baron Grey de Rotherfield, KG (9 October 1300 – September 1359) was an English soldier and courtier.John was the son and heir of Sir John de Grey, 1st Baron Grey de Rotherfield, by Margaret who was daughter William de Odingsells and the granddaughter of Ida II Longespee.John de Grey of Rotherfield was a founding member of the Most Noble Order of the Garter.He is often confused with John Grey of Codnor, who bore the same coat of arms ("Barry argent and azure").By December 1349, John was Lord Steward of the Royal Household of King Edward III.He distinguished himself well in the Scotch and French wars.He was summoned to parliament often from 1338 to 1357, and is regarded as having become Baron Grey of Rotherfield.Note: Some sources describe him as 1st Baron Grey of Rotherfield, and some as the 2nd Baron Grey, numbering his father John de Grey as 1st Baron Grey (but not of Rotherfield); this can be confusing.
Knowledge 1: Roger Grey, 1st Baron Grey of Ruthin
Roger Grey, 1st Baron Grey of Ruthin (c. 1298 – 6 March 1353) was summoned to parliament in 1324.He saw much service as a soldier.Roger was the son of John Grey, 2nd Baron Grey de Wilton and Maud de Verdon.He married Elizabeth daughter of John Hastings, 1st Baron Hastings of Bergavenny, by whom he had a son who succeeded as Reginald Grey, 2nd Baron Grey de Ruthyn. [SEP] Knowledge 2: Reginald de Grey, 1st Baron Grey de Wilton
Reynold de Grey, 1st Baron Grey of Wilton( c. 1240 – 5 April 1308) was an English nobleman after whom one of the four Inns of Court is named.He was son of Sir John de Grey and grandson of Henry de Grey.The property upon which Gray's Inn sits was once Portpoole Manor held by Reginald de Grey.Reginald acquired Wilton barony through his marriage to the heiress, Matilda Cantilupe before 1252, although at the time he was a minor under the tutelage of his father, John de Grey.From his father he had inherited the Manors of Brogborough, Thurleigh and Wrest in Bedfordshire; Great Brickhill, Snellson and Water Hall, Buckinghamshire; Hemingford, Yelling, Toseland in Huntingdonshire; Kempleigh, Gloucestershire; Purleigh, Essex; Rushton, Cheshire; Ruthin, Denbighshire; Shirland and Wilton, Herefordshire.Later he was Sheriff of Nottinghamshire, Derbyshire and the Royal Forests and Constable of Chester Castle, Constable of Nottingham Castle( March 1265/ 6) and Constable of Northampton Castle( June 1267 – Jan 1267/ 8).He was Justice of Chester in 1270 and Sheriff of Cheshire( 1270 – 1274).In 1281 he was again Justice of Chester.In 1282, he was one of the three commanders appointed by Edward I of England in his campaign against Llywelyn ap Gruffudd, the rebellious Prince of Wales.This resulted in his being granted the Dyffryn Clwyd with its castle of Ruthin Castle.This great lordship passed to his descendants, until Richard Grey, 6th Baron Grey de Ruthyn, 3rd Earl of Kent sold the lordship to the crown in 1508.He was summoned to Parliament from 1295 to 1307The king demanded his presence at the English victory over the Scots at the Battle of Falkirk.His younger grandson Roger de Grey was summoned to Parliament thus becoming Baron Grey de Ruthyn.

Answer: Reginald de Grey, 1st Baron Grey de Wilton