Works of authority in the British constitution are books written by constitutional theorists that are considered to be authoritative guides to the British constitution.
The three most prominent works of authority are Walter Bagehot's The English Constitution (1867), An Introduction to the Study of the Law of the Constitution (1885) by A. V. Dicey, and A Treatise on the Law, Privileges, Proceedings and Usage of Parliament (popularly known as Parliamentary Practice), first published in 1844, by Erskine May. The former are now historical, while the latter is regularly updated to reflect developments in parliamentary procedure.