He was born posthumously on 7 September 1656 in Dublin. On 16 October 1672 he entered Trinity College, Dublin, as Fellow Commoner. On 16 August 1676 he married Letitia Coote, sister of the Earl of Bellamont. He took a strong part in promoting the accession of William III to the throne; was attainted, 7 May 1689, by the Parliament of James II, but shortly afterwards was restored. He was then sent on a mission to Denmark from July 1689 till 1692. 
From 1695 till 1698 he was the Whig M.P. for Camelford; for Dublin from 1695 till 1699; for Swords 1703-1714; for Lostwithiel 1705-1706; for East Retford 1706-1708, and for St.Michael 1715-1722. In reward for his steadfast adherence to the House of Hanover, King George I made a Commissioner of Trade and Plantations, November 1714 to December 1715. On 16 July 1716 he was created Lord Molesworth, Baron of Philipstown, and Viscount Molesworth, taking his seat on 1 July 1719. 
He was described as "A man of some literary ability and considerable insight into economic problems." Having an estate in Yorkshire as well as in County Dublin and in King's County, he was able to take a leading part in the affairs of both countries. In England he showed himself an ardent and thorough-going supporter of the Whigs, although in Ireland he opposed the Government. He lost money in the South Sea Bubble and, when appointed to serve on the committee of investigation, acted as a hostile critic of the South Sea Company. 
He died 22 May 1725 and was buried at Swords, county Dublin. His widow died intestate on 17 March 1730, "of a great cold" and was buried "very privately, Friday night late" in St.Audoen's, Dublin.

Source: Leo van de Pas