The court's jurisdiction was gradually undercut by the King's Bench and Exchequer of Pleas with legal fictions, the Bill of Middlesex and Writ of Quominus respectively. The Common Pleas maintained its exclusive jurisdiction over matters of real property until its dissolution, and due to its wide remit was considered by Sir Edward Coke to be the "lock and key of the common law". It was staffed by one Chief Justice and a varying number of puisne justices, who were required to be Serjeants-at-Law, and until the mid 19th century only Serjeants were allowed to plead there.