Sources

1) Source: Special Collections: Ancient Petitions "People mentioned: Robert Agwylon (Aguillon), knight; Edward I, King of England; Edward III, King of England; John Lovekyn, Mayor of London; sheriff of London; [Richard FitzAlan], Earl of Arundel; [Richard FitzAlan], Earl of Arundel, son of Richard FitzAlan, Earl of Arundel."Dated: 1385. External Link
http://discovery.nationalarchives.gov.uk/details/r/C9440109. Reference: SC 8/251/12503 (Data from direct source)
2) Source: Duchy of Lancaster: Deeds, Series LS "Indenture of marriage articles between William de Bohun, Earl of Northampton, and Richard, Earl of Arundel, relating to Humphrey, son of the Earl of Northampton, and Joan, daughter of the Earl of Arudel, and Richard, son of the Earl of Arundel, and Elizabeth, daughter of the Earl of Northampton."Dated: 1359. External Link
http://discovery.nationalarchives.gov.uk/details/r/C5414206. Reference: DL 27/19 (Data from direct source)
3) Source: Chancery: Inquisitions Post Mortem, Series I, Edward III "Eleanor (de Bello Monte, or Beaumont, daughter of Henry, earl of Lancaster), countess of Arundel...Writ touching the lands &c. which she held in dower or otherwise for life of the inheritance of John son of Henry son and heir of John de Bello Monte, her late husband. 16 January, 46 Edward III...John de Bello Monte died in seisin of the premises, and on his death Henry his son and heir, being of full age, entered thereon and granted them with the king’s licence to Richard earl of Arundel and Eleanor his wife for her life, with reversion to himself and his heirs...She died on 12 January last."Dated: 1372. External Link
https://www.british-history.ac.uk/inquis-post-mortem/vol13/pp214-226. Reference: C 135/232/9