Thomas Gleadowe-Newcomen, 2nd Viscount Newcomen

Gleadowe-Newcomen succeeded his father as a Knight of the Shire for County Longford in 1802, a seat he held until 1806.

However, as this was an Irish peerage, it did not entitle him to a seat in the House of Lords.

[citation needed] Lord Newcomen died in January 1825, aged 48, when all his titles became extinct.

[citation needed] Newcomen never married, but had a long-term relationship with Harriet Holland, who bore him eight children.

One of their daughters Theresa Newcomen (1809–1853) married firstly Captain Richard Howe Cockerell RN (1798–1839), a nephew of Sir Charles Cockerell, and had issue three daughters: Theresa Cockerell married again 1841 Archibald Montgomerie, 13th Earl of Eglinton as his first wife, and bore him three sons (of whom two succeeded successively to the earldom) and one daughter.