King's County had a small electorate, probably under 1,000: in 1784 it was estimated to be 900 (each elector had two votes). It appears to have been a relatively quiet county. The Parsonses of Birr Castle usually controlled one seat and a combination of local interests, often led by the Lloyd family, the other. The most constant interest was that of the Parsonses, who had 'a very good interest and a good estate in this country'. Furthermore they combined residence with ability. The Lloyds were joined by the independent smaller interests, although they themselves also had a 'good estate', and they owned with the Parsonses a joint estate at Tibrid, which both had bought from the Baldwin family. The Blundell interest, strong at the beginning of the century, moved to England and was ennobled. Their estates eventually came into the Hill family, Marquesses of Downshire, by the marriage in 1786 of their ultimate heiress, Mary Sandys, to Arthur Hill (1016), 2nd Marquess of Downshire.
At the general election of 1761 the sitting MPs were returned: William Parsons polled 552 votes, Henry Lyons 441, and the unsuccessful contender was Henry Lestrange (1228), who polled 383. Lestrange had been MP for Banagher (1735-60) for most of the parliament of George II. In 1776 the votes were: Sir William Parsons 965, John Lloyd 708, Thomas Coghlan (0433) 485. The Sheriff declared Sir William Parsons and John Lloyd duly elected.227 Henry Lyons died without a male heir in 1783. These returns show the general pattern for the century. Other local interests included the Burys, Lords Charleville, but many of the other interests, such as the Dalys, had their principal residence elsewhere.
King's County had the boroughs of Banagher and Philipstown.