Hamilton came of a distinguished and wealthy Irish landowning family, which could boast of two extinct peerages. The revival of these honours under the title of Lord Clanbrassil was his dearest ambition. He was the first of his family to represent county Dublin which he gained after a contest in 1797, together with his poor relation Frederick John Falkiner. He opposed the Union and was at first thought likely to join opposition at Westminster, but this did not then occur. He was described as ‘well inclined’ to government though unable to attend in November 1801, and although government were neutral towards him in the county election in 1802, headed the poll with ease and applied to be governor of the county. He surprised ministers by voting with opposition on the Prince of Wales’s debts, 4 Mar. 1803, but at this time he seems to have been swayed by Falkiner’s political leanings. He was described in February 1804 as one of the Prince’s friends sailing from Ireland, though it does not appear that he voted with opposition.
In May 1806 he and Falkiner appealed for the support of the Grenville ministry at the next election, Hamilton also asking that his brother John might become chairman of the county sessions. Lord Spencer noted that Hamilton, unlike Falkiner, had not given his vote to government on 30 Apr., but he was thought ‘disposed to support’, being doubtless anxious to conciliate the strong Catholic and Whig elements in his constituency. Even so he voted with the Portland administration following the dismissal of Lord Grenville’s, 9 Apr. 1807, and was reckoned a supporter of the new government. George Ponsonby believed that Hamilton might have been retained by his friends had they promised to bestow on him the first Irish peerage available.
Thus frustrated, Hamilton could not be counted on for attendance. He was in the government lobby on the Scheldt inquiry, 26 Jan. 1810, but despite a summons to attend, paired off on the same question in March. He voted against the reform of sinecures, 17 May, and of Parliament, 21 May 1810, but for the first time voted for the Catholic claims, and was absent without leave on the Regency. He again supported the Catholic claims, 31 May 1811, and annoyed government by supporting Morpeth’s critical motion on Ireland, 4 Feb. 1812. On the other hand, he still opposed the regulation of sinecures, 7, 24 Feb., 4 May, and was in the government minority against Stuart Wortley’s motion, 21 May 1812. Yet he had again voted for Catholic claims on 24 Apr. and was reported as being unwilling to go into opposition with Lord Liverpool at that time.
On the eve of the election of 1812, Hamilton again applied for an Irish peerage, feeling confident that Falkiner could now succeed him as county Member, but government were unable to comply and Hamilton was re-elected. He voted for the Catholic claims on 2 Mar., 13 and 24 May 1813, and otherwise with government. They humoured him by realizing his wish to be a county governor and by patronage for one of his brothers.
