Thomas Southwell, 1st Baron Southwell

He was the oldest son of Richard Southwell, son of Sir Thomas Southwell, 1st Baronet, and his wife Lady Elizabeth O'Brien, daughter of Murrough O'Brien, 1st Earl of Inchiquin.

[3] In 1681, his father having predeceased him, Southwell succeeded his grandfather as baronet.

[4] During the Glorious Revolution of 1689, after he led an unsuccessful rising in County Galway, he and his brother were attainted by the parliament of King James II of England.

[5] In 1695, Southwell entered the Irish House of Commons for County Limerick, representing it until 1713.

[6] He was returned for the constituency again from 1715 until August 1717,[6] when he was elevated to the Peerage of Ireland as Baron Southwell, of Castle Mattress, in the County of Limerick.