St Johnstown was incorporated by a 1628 charter of 3 Chas I; a further charter, similar but giving new names, was granted by James II in 1690 but was probably never acted upon. The Charles I charter included a grant of 86 acres and the obligation to found a town on some part of it. The first sovereign was Walter Lecky, and the first burgesses were Walter Lecky, Sir James Ware, Capt. Arthur Forbes, Arthur Forbes, George Ffilawne, William Hithcock, Richard Wynne - merchant, Thomas Kennedy - maltman, Robert Wright - carpenter, Isaac Kane - tailor, George Cunningreve - tanner and William White - weaver. It was soon dominated by the Forbes family, Earls of Granard from 1684. Although the conduct of the family at the Revolution had been uncertain - the 2nd Earl served under Turenne - they survived, and his son, the 3rd Earl, at the time of his death in 1734 was the senior admiral in the British navy. His son, John (0777), was possibly the most distinguished representative of the borough (1751-60). He was Admiral of the Fleet and General of Marines, and entered a strong protest against the execution of Admiral Byng in 1757. He said that he came in 'to preserve the peace of the country', so the family interest in 1751 may still have required bolstering by at least the return of a member of the family.
By 1783, St Johnstown was composed of 'Burgesses and Freemen. Freemen gone into disuse. Gentlemen possessed of Burgess plots, not allowed to vote. Patron, Lord Granard', and the borough was 'at the absolute disposal of the Patron'.265 By 1790:
This Borough is entirely devoted to the interest of Earl of Granard its few electors, whose number is easily reckoned, owing their existence to his Lordship's nomination and complaisantly acquiescing in his recommendation of their representatives. Since the accession of the present noble Earl to the honours of his house, it has never been sold, his just sense of what is due to his own character and station forbidding such despicable traffic, but he has honoured with his protection and interest, with the Burgesses, men whose principles he knew and on whose honour he could depend he acts as an honest trustee for the public and leaves his friends as free as he desires to be himself under no influence but that of their own reason, under no other bias than the suggestions of their own understanding. Such liberality of conduct in the proprietors of Boroughs is not often experienced.266
St Johnstown was disfranchised at the Union and the £15,000 compensation was awarded to George, 6th Earl of Granard.
