| Constituency | Dates |
|---|---|
| Old Sarum | 5 Jan. 1742 – May 174726 Feb. 1746 – May 1747 |
| Bridport | 25 May 1747 – 1754 |
| Buckingham | 1754 – 1761, , 1757 – 17681766 – 1768 |
| Horsham | 1768 – Mar. 1770 |
Dep. paymaster of forces May 1745–1755; ld. of Trade 1746 – Dec. 1755; ld. of Treasury Nov. 1756 – Apr. 1757, July 1757 – Mar. 1761; cofferer of the Household Mar. – Oct. 1761; P.C. 3 Apr. 1761; jt. vice-treasurer [I] Aug. 1766-Jan. 1770.
In 1754 Grenville was returned unopposed on Lord Temple’s interest. Throughout his parliamentary career he was a faithful supporter of William Pitt; resigned with him in October 1761, and vigorously opposed Bute’s Administration and that of his own brother George Grenville. Though he spoke fairly often in the House, his speeches, which seem to have been tedious, were usually but briefly mentioned. Still, when on 24 Nov. 1763 Richard Rigby condemned Lord Temple as the instigator of Wilkes and the mob, James Grenville, according to Horace Walpole,1Mems. Geo. III, i. 260.
rose, in amazing heat, to defend his brother and vomited out a torrent of invectives on Rigby ... the bitterest terms flowing spontaneously from him who had ever been the most obscure and unready speaker; and what added to the outrage of the diction was, that sitting on the bench immediately above Rigby, and dashing about his arm in the air, he seemed to aim blows at the latter, who was forced to crouch lest he should receive them.
In 1765, during negotiations for a new Administration, James Grenville was mentioned on 15 May as treasurer of the navy or secretary at war, and on 30 June and 5 July as joint vice-treasurer of Ireland.2Fortescue, i. 93, 126, 137. According to Horace Walpole, Grenville genuinely regretted the necessity to refuse the Rockinghams’ offer of this post;3Mems. Geo. III, ii. 140. and even in November Newcastle had hopes that he would accept.4Add. 32971, f. 289. In July 1766 Chatham offered Grenville the joint vice-treasurership of Ireland, and subsequently the presidency of the Board of Trade or the pay office; and at his own request he was appointed joint vice-treasurer.5Chatham Corresp. ii. 466.
James Grenville’s adherence to Pitt after the latter’s estrangement from Temple prevented him from standing again at Buckingham in 1768, and Grafton arranged for his return at Horsham on the Irwin interest. His political enthusiasm seems by this time to have waned: no votes or speeches by him are reported during this Parliament, and when early in January 1770 he resigned office it was, according to Walpole, ‘unwillingly, to gratify the violence of his brothers’.6Mems. Geo. III, iv. 37. Next he decided to leave Parliament, and on 16 Jan. Grafton wrote to Lord Irwin: ‘Mr. James Grenville was with me to-day wishing to accept of some office in order to clear himself from the political difficulties in which he found himself entangled’; on 20 Jan. Irwin was informed by his agent that Grenville had declared that ‘family connexions etc. had made it unavoidable’.7HMC Var. viii. 184, 185. On 19 Feb. 1779 Grenville wrote to Lady Chatham:8Chatham Corresp. iv. 423.
I have long pursued the path of private life, and have adhered to that plan. I chose it under circumstances many years past, from knowing myself of too little capacity or consequence to do good, and from having an invincible dislike to doing harm.
He died 14 Sept. 1783.