Thomas Southwell, 2nd Baron Southwell

In 1717, Southwell entered the Irish House of Commons for County Limerick, the same constituency his father had represented before,^[1] and sat for it until 1720, when he succeeded him also as baron.^[5] In 1726, Southwell was sworn of the Privy Council of Ireland.^[6] He became a Fellow of the Royal Society in 1735^[7] and was Governor of County Limerick until his resignation in 1762.^[8]

In March 1719, he married Mary Coke, eldest daughter of Thomas Coke, and by her he had three sons.^[8] Southwell died at Craig's Court, Charing Cross, aged 68 and was succeeded in his titles by his eldest surviving son Thomas.^[8] His younger brother, Edmund Southwell, "lived in intimacy with"^[9] Samuel Johnson for many years, and was the first to introduce the great Shakespearean scholar Edmond Malone to him.^[9]

• Boswell, James (1824). The life of Samuel Johnson, LL.D. London: G. Cowie.
• Burke, John (1832). A Genealogical and Heraldic History of the Peerage and Baronetage of the British Empire. Vol. II (4th ed.). London: Henry Colburn and Richard Bentley.
• Johnston-Liik, Edith Mary (2006). MPs in Dublin: Companion to History of the Irish Parliament 1692–1800. Ulster Historical Foundation. ISBN 1-903688-60-4.
• Lodge, Edmund (1838). The Genealogy of the Existing British Peerage (6th ed.). London: Saunder and Otley.
• Lodge, John (1789). Archdall, Mervyn (ed.). The Peerage of Ireland or A Genealogical History of the Present Nobility of that Kingdom. Vol. VI. Dublin: James Moore.
• Lundy, Darrel (24 November 2009). "Thomas Southwell, 2nd Baron Southwell of Castle Mattress". thePeerage.com. Retrieved 8 January 2011.^{[unreliable source]}
• Rayment, Leigh (23 January 2010). "Privy Council of Ireland". Leigh Rayment's Peerage Page. Archived from the original on 7 June 2008. Retrieved 8 January 2011.^{[unreliable source]}
• The Royal Society (2009). "Southwell; Thomas (1698–1766); 2nd Baron Southwell". Library and Archive catalogue. The Royal Society. Retrieved 8 January 2011.
• Waite, Arthur Edward (2007). A New Encyclopedia of Freemasonry. Vol. I. Cosimo. ISBN 978-1-60206-641-0.