In 1692 and 1693, John Barclay served in the East New Jersey General Assembly, representing the Town of Perth Amboy. On November 25, 1695, Barclay was appointed Deputy Provincial Secretary and Register, succeeding Thomas Gordon, who had returned to Great Britain. On August 6, 1698, he was appointed Register of the Court of Chancery and as a Commissioner of the Court of Small Causes.Contributions to the Early History of Perth Amboy and Adjoining Country, William A. Whitehead, D. Appleton & Co., New York, 1856, p 42-43 He returned to the Legislature in 1698 and 1699, this time representing Middlesex County.Manual of the Legislature of New Jersey, date: various (pre 1950)
