Cork city, the second city in the kingdom, grew in wealth, size and importance through the century, and apart from Dublin it was the only borough to send two members to the Westminster parliament after the Union. By the middle of the century its population was estimated at 'above 100,000'. As a county borough it combined the characteristics of both electorates. The earliest charter found by the Commissioners to Inquire into Municipal Corporations was the 1242 charter of 26 Henry III. The franchise was vested in the freeholders of land in or around Cork, and freedom of the city could be acquired by birth, marriage or grace, freedom by birth or marriage being confined to the freeman's eldest son and eldest daughter's husband. The influence of the corporation was probably in the hands of the merchants, who, as many were Roman Catholics, were prevented by denominational restrictions from exercising the full weight of their economic power. The Boyle/Shannon influence was also a factor; it was based on property, patronage and prestige. The denominational situation, which weakened the political power of the merchants, probably enhanced Lord Shannon's.
All the members for Cork had personal influence within the city, and their selection was usually indicative of hoped-for advantages to the city. The Brodricks were possibly the most powerful politicians of the 1692 to 1715 period. Robert Rogers was Deputy Governor of Cork in 1799, a strong Protestant and a prominent city politician. Thomas Erle was Commander-in-Chief of the army in Ireland. He was a Lord Justice for a fortnight in 1702, and again in 1703/4. Speaker Boyle and the merchants were usually in accord. Edmond Knapp was an Alderman and a former Mayor. Hugh Dixon was Colonel of the Cork Militia, and both he and Emanuel Pigott were involved with establishing the Workhouse and rebuilding Cork Cathedral. Edward Webber began, at his own expense, the Mardyke Walk, which was one of the amenities of Cork.
In 1761 Cork returned the greatest wheeler-dealer of all its sons, John Hely-Hutchinson, who represented the city in four successive parliaments and then ensured the return of his son in his place. Throughout his long political career Hely-Hutchinson was always mindful of the views and opinions of his constituents, and took a detailed interest in trade or anything, such as an embargo, that might affect them: for instance, he was deeply involved in the trade negotiations of the late 1770s, and in August 1782 the Chief Secretary, Richard Fitzpatrick, wrote to him that: 'At all events I flatter myself your constituents at Cork will see that their interests have been attended to, and that your influence with administration here has been so far successfully exerted in their favour as to procure a recommendation of the proposed means to the other side of the water, which was everything they had in their power to do.'117 It was said that 'He recommended himself by his attention to the principle [sic] merchants, a man of eloquence and excellent persuasion, which talents operated wonderfully among the multitude at his beginning. Being ambitious to aspire and having no other means he absolutely practiced sedition; he would prostitute his conscience to advance his relations, who are very poor for he is but of mean rank and birth.'118
In 1768 the electors of Cork, with a view to government patronage and commercial advantages, chose as their other representative William Brabazon Ponsonby, John Ponsonby's eldest son. By so doing, 'The citizens of Cork imagined to secure themselves great benefits by his interest.'119 At this time Lord Shannon was allied with the Ponsonbys by marriage and also in politics. Under these circumstances it was unfortunate for them that the power of the Ponsonby family was so soon curtailed. In the election of 1776 Ponsonby was replaced by Richard Longfield, who was at that time 'attached to Lord Shannon', but afterwards Longfield became hostile to Lord Shannon and developed his own interest, 'which is principally in the corporation'.120
After 1783 the Shannon interest suffered a reversal from the Longfields, and three distinct interests then emerged: the Shannon, the corporation interest of the Longfields and the 'popular' interest of the Hely‑Hutchinsons, which they retained until well after the Union.121 Freemasonry also played a part in Cork city politics, but this is more difficult to assess.