He was also Clerk of the hanaper for life from 1771. In later life Fitzsimon held the lucrative office of Clerk of the Crown and Hanaper. Co. Dublin, Clerk of the Hanaper and M.P. for County Dublin. Paid in the hanaper has respited his homage until Whitsuntide next. He took up the role of joint clerk of hanaper in reversion in November 1714. Clerk of the Hanaper became an office in the department of the chancery, now abolished.