Thomas de Berkeley, 5th Baron Berkeley Thomas de Berkeley, 5th Baron Berkeley Thomas de Berkeley, 5th Baron Berkeley (5 January 1352/53 – 13 July 1417), "The Magnificent", of Berkeley Castle and of Wotton-under-Edge in Gloucestershire, was an English peer and an admiral. 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". He was born at Berkeley Castle in Gloucestershire, the son and heir of Maurice de Berkeley, 4th Baron Berkeley by his wife Elizabeth le Despencer. In
Maurice Berkeley, 3rd Baron Berkeley was disinherited by his elder brother William Berkeley, 1st Marquess of Berkeley, 2nd Baron Berkeley (1426–1492), who died without surviving progeny. As he never therefore possessed Berkeley Castle, he had no claim to the ancient feudal barony of Berkeley, which was dependent on landholdings. It was assumed (according to a very unusual legal rationale) that the barony by writ created in 1412 was also held dependent on the tenure of Berkeley Castle (that is to say it was deemed a feudal barony or barony by tenure), and that it had thereby been forfeited by association, and thus Maurice never assumed