Like his father, who joined Brooks’s in July 1807, Knox entered Westminster politics as a supporter of Lord Grenville. In March 1809 he was presented at court and put up for Brooks’s by the duke of Devonshire. The family were not thought to be especially loyal to the crown, despite their rich pickings from government. He soon returned to Ireland and, according to Mrs. Spencer Stanhope, was
heartily glad to get from his mamma’s introductions. When he was introduced to the duke of Gloucester, H.R.H. inquired what profession he was brought up to, and at the reply, exclaimed, ‘What, no profession!’ Mrs. Knox, who had presented him as an eldest son, coloured.Spencer-Stanhope Letter-Bag, i. 175-6, 178.
In January 1810 he went with John Spencer Stanhope to the Peninsula, but after a few months in Portugal he abandoned his companion, who recorded that ‘to quarrel with Knox was impossible, for there lives not a man of a more amiable or kind hearted disposition’.
He was returned unopposed for Dungannon in 1820 and at the following two general elections. His only known vote that year was for inquiry into Anglo-Irish trade, 14 June. He divided in defence of ministers’ conduct towards Queen Caroline, 6 Feb., against Catholic relief, 28 Feb., and for the forgery punishment mitigation bill, 4 June 1821. He followed the duke of Buckingham’s lead in adhering to administration at the start of 1822 and was thereafter reckoned an inflexible ministerialist in the Commons, where he sat on several Irish select committees.
Knox divided for Catholic relief, 6 Mar. 1827. It was probably he, not his brother John Henry, now Member for Newry, who was appointed to the select committee on the corporation of Northampton, 21 Feb., and who voted against the Coventry magistracy bill, 18 June 1827. Having brought up pro-Catholic petitions, including one from Drumglass parish, in which his constituency lay, 22 Feb., he voted for repeal of the Test Acts, 26 Feb., and Catholic relief, 12 May 1828. He complained about Waithman’s comment that Members were slavish clients of their patrons, 27 June, unless this intervention was by his brother, whom he joined in voting with the Wellington ministry against the reduction of the salary of the lieutenant-general of the ordnance, 4 July 1828. Listed by Planta, the patronage secretary, as a possible mover or seconder of the address at the start of the 1829 session, he was considered likely to side ‘with government’ for Catholic emancipation.
Knox’s father, who voted by proxy for reform in the Lords, was rewarded with the Irish earldom of Ranfurly in September 1831. It was thus under the courtesy title of Viscount Northland that Knox, a Conservative, represented Dungannon as a stopgap, 1837-8. On Ranfurly’s death in 1840 he succeeded to his titles and properties, including the bulk of personal wealth sworn under £30,000 in Ireland and £40,000 in England.
