In August 1415, John was granted the lands that his brother, Thomas (deceased), had forfeited. He fought at the Battle of Agincourt on 25 October 1415. In 1417, John was Captain of Mortagne and the king granted John the castle and lordship of Tilly in Normandy in November of that year. John was created a Knight of the Garter about 1418/9. On 31 January 1418/9 he was given the comte of Tancarville in Normandy in tail male, (Earl of Tankerville). In March of that year he was appointed joint commissioner to treat with the French ambassadors. He served as Captain of Mantes in 1419 and as Captain of Harfleur in 1420. He was also appointed hereditary grand chamberlain of Normandy and governor of Tournay. He was 6th Lord of Powys, in right of his wife, but only held the title for a week, as John died eight days after his father-in-law.
John married Joan de Cherleton, elder daughter and co-heiress of Edward Cherleton (or Charleton), K.G., 5th Lord Cherleton) and his first wife, Eleanor Holland. Joan was born about 1400/1 (aged 21 in 1421, aged 24 in 1425). The date of their marriage is unknown and is estimated. They had one son:
Henry Grey, Knt., 2nd Count of Tancarville, born about 1418/9, died 13 January 1449/50, married Antigone of Gloucester and had issue
↑ 1.01.1 Douglas Richardson. Magna Carta Ancestry: A Study in Colonial and Medieval Families, 4 vols., ed. Kimball G. Everingham. 2nd edition. Salt Lake City, UT: the author, 2011, vol. II, page 254-255 GRAY 7.ii.
↑ 3.03.13.23.33.43.5 Douglas Richardson. Royal Ancestry: A Study in Colonial and Medieval Families, 5 vols., ed. Kimball G. Everingham. Salt Lake City, UT: the author, 2013, vol. III, page 588.
↑ 4.04.14.24.220.127.116.11.74.8 Cokayne, George Edward and H.A. Doubleday et. al eds. Complete Peerage of England, Scotland, Ireland, Great Britain and the United Kingdom, Vol. VI: Gordon to Hurstpierpoint, 2nd edition. (London, 1926). Online at FamilySearch.org, pages 136-138: Grey of Powis
↑ 5.05.15.25.3 Hope, Sir William Henry St. John. The Stall Plates of the Knights of the Order of the Garter, 1348-1485. (A. Constable and Co., Westminster, 1901). Online at Google Books, plate XXVIII.
Richardson, Douglas. Magna Carta Ancestry: A Study in Colonial and Medieval Families, 4 vols., ed. Kimball G. Everingham. 2nd edition. (Salt Lake City, UT: the author, 2011). See also WikiTree's source page for Magna Carta Ancestry.
Richardson, Douglas. Royal Ancestry: A Study in Colonial and Medieval Families, 5 vols., ed. Kimball G. Everingham. (Salt Lake City, UT: the author, 2013). See also WikiTree's source page for Royal Ancestry.
Richardson, "Royal Ancestry", (2013), vol. II, page 143.