King joined the army of occupation in France in 1816 and was remembered as ‘good natured and popular in the service’. In 1825 he was granted leave of absence from his regiment pending a ‘promotion to a company’, which never occurred.
He was probably the ‘Sir Robert King’ who unsuccessfully attempted to present a petition defending the legitimacy of Daniel O’Connell’s return for county Clare, 26 Feb., and he voted for allowing him to take his seat unhindered, 18 May 1829. He voted for the Wellington ministry’s concession of Catholic emancipation, 6, 30 Mar., insisting that it was supported by the ‘great majority’ of his Protestant constituents, 9 Mar., when he dismissed a hostile county Cork petition brought up by Moore, Member for Dublin, as ‘the machinations of a junto in the city of Cork, styled Brunswickers’ who ‘utter language ... almost treasonable’. He presented and endorsed a counter-petition, 12 Mar. It is not clear whether it was he or his namesake who had been listed by Planta, the Wellington ministry’s patronage secretary, as being ‘opposed to securities’; but on 12 Mar. he conceded the ‘propriety of disfranchising the Irish 40s. freeholders’ and urged the same to be applied in England, where there was no ‘mode of doing this, except ... reform’. He brought up constituency petitions against militia reductions, 25 Mar. He presented and endorsed one against the ‘disastrous’ Irish Subletting Act, 7 May 1829, when he advocated the introduction of a ‘modified system of poor laws’, which would ‘compel absentee proprietors, drawing large revenues ... to contribute ... to the relief and support of their suffering countrymen’. Speaking in similar terms, he called for a ‘heavy tax upon the property of those who absent themselves’, 5 Mar. 1830. It was probably his namesake who had been listed by the Ultra leader Sir Richard Vyvyan* as a supporter of the Wellington ministry in October 1829, and who voted against parliamentary reform, 18 Feb., the enfranchisement of Birmingham, Leeds and Manchester, 23 Feb., Jewish emancipation, 5 Apr., 17 May, and reducing the grant to South American missions, 7 June 1830. It was he, however, who divided in the minority with ministers on the Bathurst and Dundas pensions, 26 Mar., for on the hustings later that year he defended his vote, saying he had thought ‘it was the custom to give superannuation pensions to persons filling these offices’.
At the 1830 general election he was again returned unopposed.
At the 1832 general election he offered again for county Cork as a Liberal against two Repealers and two Conservatives and came bottom of the poll. He stood as a Conservative in 1837 but was again defeated. He succeeded his elder brother as Viscount Kingsborough that year, and his spendthift father, who had started to go insane in 1830, as 4th earl of Kingston in 1839, by when the family estates were so indebted that creditors had begun to take action. In 1844 his Irish estates were seized by the encumbered estates court in Dublin, and by 1856 nearly 71,000 acres and ‘a large quantity of silver and plate’ had been sold.
