Boyle was incorporated by a charter of 1614, 11 James I. A charter was also granted by James II in March 1789/90, but it was never used. The corporation consisted of a burgomaster, 12 free burgesses and a commonalty of unspecified numbers. The King family, who arrived in Ireland during the reign of Elizabeth I, controlled the borough throughout the period: Sir John King (1159) sat in the 1695 parliament of William III and they sat in the parliaments of Anne, George I, George II and George III. By the end of the century they were Earls of Kingston. In 1783 Boyle consisted of c. 2,000 inhabitants, about 300 of whom were Protestants,342 and it had some resident freemen. In 1790 it was reported that:
This Borough has long been under the influence of the King family, the head of which, the Earl of Kingston (1150), is its present proprietor and private property it may very justly be called, as its sole electors are an inconsiderable number of burgesses, who are chosen into office by the mandate of the noble Earl, whose patronage is, of course, omnipotent in the choice of its representatives.
From his rank and fortune we should naturally expect that it would never be exposed to sale, but that some of his own family and connections would always represent it. But the reverse is the fact and at this present moment Mr Robert Boyd (0199) sits as Member for it in the House of Commons, the representative of his own money, and not the selected trustee of the Earl's confidence.343
Actually members of the King family did very often represent it. Boyd was an ambitious lawyer who was elevated to the bench in 1791, so he sat only for the 1783-90 parliament, and the other MP was a King. One of the family also sat in the following parliament. It was disfranchised by the Act of Union; the £15,000 compensation was paid to the Earl of Kingston.