Robert Nugent married secondly, 23 March1736, Anna (died 22 November1756), daughter of James Craggs, the secretary of state, and sister of the Right Honourable James Craggs, whereupon Robert Nugent adopted the surname of Craggs-Nugent. She had already been twice given in marriage, but Robert, who was born a Roman Catholic, had abandoned his Church very early in life. He was tersely described by Richard Glover as a jovial and voluptuous Irishman who had left popery for the Protestant religion, money and widows.
His wife's property included the borough of St Mawes in Cornwall, and Nugent sat for that constituency from 1741 to 1754, after which date he represented Bristol until 1774, when he returned to St Mawes. In 1747 he succeeded Lord Doneraile as Comptroller of the Household to the Prince of Wales. Nugent lent the Prince large sums of money, which were never repaid; the appointments and peerages he received later in life have been attributed to the wish of the Prince of Wales's son, George III, to compensate Nugent.