According to a contemporary, O’Neill ‘could not be called a good looking man, he had dark staring eyes, rather pale complexion and slightly pitted with the smallpox, with hair having a tendency to curl’.
Little was known of O’Neill when he made a speculative visit to Hull shortly before the 1826 general election. The Hull Rockingham declared that it knew nothing of him: ‘We suspect that he does not know all who may be useful to him in his electioneering campaign, or he would not have presented himself as third man, when neither a first nor second has entered the field’. He had in fact invited the burgesses to sign a requisition requesting him to stand. Between 500 and 700 did so, and ten days before the nomination he made his appearance. The rumour in the town was that he had come to Hull to contest a seat as a result of a wager struck at his London club. The truth of this is unknown, but he pursued an active campaign, taking care to cultivate the wives of the freemen, an observer describing him as ‘one of the very best canvassers I ever met’. According to another witness
he had a fair display of jewelry, which he took good care to show. His manners were very volatile, and to look at the man, a keen observer would say that he really could not make up his mind to imagine that he was firm in his statements for there was a flightiness of manner about him. He looked as wild and harum-scarum as an untrained colt, yet, he was possessed of sufficient suaviter in modo to carry his point.
He quickly established his popularity with the lower order of freemen and in his published address, in which he described himself as a relative of the earl of Antrim and Sir George Fetherston*, cited his support for free trade and a revision of the corn laws, and his hostility to Catholic emancipation. After an acrimonious contest, in which he boasted of connections that would benefit the people of Hull and promised that a ship of 800 tons would be built there if he was elected, he was returned at the head of the poll. At the declaration he described his victory as that of the ‘independent freemen’ over ‘powerless Whiggism’, while the Hull Packet attributed his success ‘to an active and assiduous canvass, and to his frequently addressing the public’.
Soon after entering the House, O’Neill had some dealings with John Cam Hobhouse* concerning his collection of Byron’s works.
During the early months of 1830 O’Neill’s health faltered and he suffered a further blow when his father died that April. The Hull Rockingham of 10 July reported various rumours that his arrival in the town was imminent but doubted them. William Denison*, advising Gilbert John Heathcote* on his pretensions to Hull, informed him, 16 July, that ‘O’Neill, not having paid his bill, cannot stand’. He was also suspected of being involved in a gambling scandal. Nevertheless, he issued a statement professing an intention to return, citing his ‘adherence to the cause of Protestant ascendancy’, his defence of the voters of East Retford and his attempts to ‘narrow the power of the great, and extend that of the people’. Summing up his politics, he declared, ‘though returned on what is called the Tory interest, I neither did, nor could, give a regular support to government’. Although his election committee reformed to draw up a formal requisition to him, very few signed it, and no one of any great consequence in the town. As a result O’Neill retired at the 1830 dissolution.
He returned to politics in the 1840s, trying to secure a quay for Bunowen and offering Peel, as premier, his services and advice on Irish matters. Reconciled to Catholic emancipation, he apologized to Peel for the criticisms he had made of him in 1829 and was granted an interview with him in the autumn of 1844, when he declared his intention of returning to the House.
