Question: Who is the paternal grandfather of Gilbert De Umfraville, Earl Of Angus?

Knowledge 1: Gilbert de Umfraville, Earl of Angus
Gilbert de Umfraville, Earl of Angus(r. 1246–1308) was the first of the Anglo-French de Umfraville line to rule the Earldom of Angus in his own right.His father was Gilbert de Umfraville (d. shortly before 13 March 1245), a Norman, and feudal Baron of Prudhoe in Northumberland, and his mother was Matilda, Countess of Angus.He succeeded his father in infancy.He also carried on the line of the earlier Gaelic earls through his mother.He succeeded her sometime after 1247 (when she was still living with her third husband Richard de Dover) as an infant, certainly no older than three.
Simon de Montfort, 6th Earl of Leicester, paid £10,000 to act as Gilbert's warden.Gilbert eventually grew into his inheritance, and although he was primarily an English magnate, there are still a few of his recorded grants.Gilbert was the nominal ruler of the province for more than half a century.As Earl of Angushe was summoned in 1276 for a campaign in Gwynedd against Llywelyn ap Gruffudd.In 1284 he attended the parliament with other Scottish noblemen who acknowledged Margaret of Norway as the heir to King Alexander.In 1296 he again joined Edward I in his conquest of Scotland.He also founded a chantry for two priests at Prudhoe castle to celebrate mass daily.He died in 1308, and was succeeded by his second son, Robert de Umfraville, Earl of Angus.Gilbert was buried in Hexham Abbey his effigy survives and can be seen. [SEP] Knowledge 2: Gilbert de Umfraville
Gilbert de Umfraville (died 1245) was a 13th-century baron.Gilbert was the eldest son of Richard de Umfraville, Lord of Redesdale.He succeeded his father as Lord of Redesdale and Baron Prudhoe from 1226 at his seat of Prudhoe Castle.He also had lands at Otterburn.
Knowledge 1: Gilbert de Umfraville, Earl of Angus
Gilbert de Umfraville, Earl of Angus(r. 1246–1308) was the first of the Anglo-French de Umfraville line to rule the Earldom of Angus in his own right.His father was Gilbert de Umfraville (d. shortly before 13 March 1245), a Norman, and feudal Baron of Prudhoe in Northumberland, and his mother was Matilda, Countess of Angus.He succeeded his father in infancy.He also carried on the line of the earlier Gaelic earls through his mother.He succeeded her sometime after 1247 (when she was still living with her third husband Richard de Dover) as an infant, certainly no older than three.
Simon de Montfort, 6th Earl of Leicester, paid £10,000 to act as Gilbert's warden.Gilbert eventually grew into his inheritance, and although he was primarily an English magnate, there are still a few of his recorded grants.Gilbert was the nominal ruler of the province for more than half a century.As Earl of Angushe was summoned in 1276 for a campaign in Gwynedd against Llywelyn ap Gruffudd.In 1284 he attended the parliament with other Scottish noblemen who acknowledged Margaret of Norway as the heir to King Alexander.In 1296 he again joined Edward I in his conquest of Scotland.He also founded a chantry for two priests at Prudhoe castle to celebrate mass daily.He died in 1308, and was succeeded by his second son, Robert de Umfraville, Earl of Angus.Gilbert was buried in Hexham Abbey his effigy survives and can be seen. [SEP] Knowledge 2: John Comyn (died 1242)
John Comyn, Earl of Angus jure uxoris, was a son of William Comyn, Lord of Badenoch later the Earl of Buchan and became the Earl of Angus, jure uxoris of his wife Matilda, heiress of Máel Coluim, Earl of Angus.He died in 1242.
Knowledge 1: Gilbert de Umfraville, Earl of Angus
Gilbert de Umfraville, Earl of Angus(r. 1246–1308) was the first of the Anglo-French de Umfraville line to rule the Earldom of Angus in his own right.His father was Gilbert de Umfraville (d. shortly before 13 March 1245), a Norman, and feudal Baron of Prudhoe in Northumberland, and his mother was Matilda, Countess of Angus.He succeeded his father in infancy.He also carried on the line of the earlier Gaelic earls through his mother.He succeeded her sometime after 1247 (when she was still living with her third husband Richard de Dover) as an infant, certainly no older than three.
Simon de Montfort, 6th Earl of Leicester, paid £10,000 to act as Gilbert's warden.Gilbert eventually grew into his inheritance, and although he was primarily an English magnate, there are still a few of his recorded grants.Gilbert was the nominal ruler of the province for more than half a century.As Earl of Angushe was summoned in 1276 for a campaign in Gwynedd against Llywelyn ap Gruffudd.In 1284 he attended the parliament with other Scottish noblemen who acknowledged Margaret of Norway as the heir to King Alexander.In 1296 he again joined Edward I in his conquest of Scotland.He also founded a chantry for two priests at Prudhoe castle to celebrate mass daily.He died in 1308, and was succeeded by his second son, Robert de Umfraville, Earl of Angus.Gilbert was buried in Hexham Abbey his effigy survives and can be seen. [SEP] Knowledge 2: William Douglas, 2nd Earl of Angus
William Douglas, 2nd Earl of Angus (24 February 1398 – October 1437) was a Scottish nobleman and soldier.The son of George Douglas, 1st Earl of Angus and Princess Mary of Scotland, he was a grandson of King Robert III.The story of Angus' life is interwoven with that of his uncle and King, James I of Scotland.Angus was born about 1398 at Tantallon Castle in East Lothian.He inherited the Earldom of Angus in 1402, following his father's death of the plague whilst in English captivity, following the Battle of Homildon Hill.

Answer: Richard de Umfraville