Thomas de Berkeley, 1st Baron Berkeley died at Berkeley Castle on 23 July 1321 and was succeeded in his titles by his eldest son Maurice de Berkeley, 2nd Baron Berkeley. Thomas de Berkeley, 1st Baron Berkeley Thomas de Berkeley, 1st Baron Berkeley (c.1251 – 23 July 1321), "The Wise", feudal baron of Berkeley, of Berkeley Castle in Gloucestershire, England, was a peer, soldier and diplomat. His epithet, and that of each previous and subsequent head of his family, was coined by John Smyth of Nibley (d.1641), steward of the Berkeley estates, the biographer of the family and author of "Lives of the Berkeleys". Thomas de Berkeley
Berkeley family docent and genealogist at the Berkeley Castle listed the Barclay clan as also descending from the de Berkeley clan through the matriarchal line Alice De Berkeley -- the woman who married Robert Fitzharding and restored the family's name. Additionally, historians on Scottish clans and surnames point out that the Barclay clan spelling moves into the Berkeley (pronounced Bar-Clay) spelling. This descends from Sir Maurice Berkeley (by 1514–81), a politician who rose rapidly in the Tudor court. He came from the Berkeleys of Stoke Gifford, a cadet branch of the main Berkeley family, as a descendant of Sir Maurice de Berkeley