Youghal was at the beginning of the century controlled by Lord Burlington, the senior descendant of the great earl, and continued so until the reign of George II, whose long reign was unpunctuated by a by-election until 1758. This was a year of particular weakness for the Boyles as the Duke of Devonshire, whose late wife was the Boyle heiress, was involved in the Seven Years' War and his mother-in-law, who had kept her eye on her grandchildren's inheritance, died. In any case the Boyle interest in Youghal had, by that time, probably passed to the Earl of Shannon. The Duke's sister, Lady Elizabeth Ponsonby, recollected that the Burlington interest had been overthrown before Lord Shannon built up his influence in the borough. Considering that the Duke entrusted his other Irish electoral interests to Lord Shannon, it is unlikely that Shannon usurped it, although a later Devonshire agent, Knowlton, declared in 1812 that this was the case.
Youghal's electors appear to have had an independent streak. Like Kinsale, it was a corporation with burgesses and freemen. In 1790 it was said that 'this is commonly considered as one of Lord Shannon's boroughs but the fact is otherwise. He certainly has an interest in the town and one that can be of great use to any candidate. But the Uniacke family have here such a prevailing interest as nothing can oppose and were his Lordship to venture a contest with them, he would soon experience the feebleness of his force. This he is much too prudent to hazard; he therefore enjoys the reputation of its patronage. Two Uniackes (2121, 2122) are returned for the town and they possessing the essentials, mind not a name.' However, the 1793 commentator favoured Lord Shannon while admitting that 'The Uniackes have some power in Youghal.'127 Before the 1797 election Lord Shannon reported to his son that 'The Youghal seigniory met at Castlemartyr, some from their town and some from Cork We went over the whole list of voters [taking a pessimistic view] they concluded on a majority of 5 in the town, but they think possibly 10; but as the country [freemen] votes we shall overpower them. I ordered dinner at 4, on their agreeing to stay and talk matters over, but Sir Edward Crofton128 (0524) and a friend of his came at 2 o'clock and deranged our politics, so all ended in a sort of drinking bout, and by 8 I sent off the militia and the corporation very happy.' In 1797 Robert Uniacke (2122) and John Keane (1128) were returned - both were friends of Lord Shannon.
Youghal retained one seat at the Union. In January 1800 Robert Uniacke was appointed Master General of the Ordnance and re-elected; however, John Keane won the Union ballot, was created a baronet and was re-elected in 1802.