The Birmingham Gun Barrel Proof House was established in 1813 by an act of Parliament at the request—and expense—of the then prosperous Birmingham Gun Trade. Its remit was to provide a testing and certification service for firearms in order to prove their quality of construction, particularly in terms of the resistance of barrels to explosion under firing conditions. Such testing prior to sale or transfer of firearms is made mandatory by the Gun Barrel Proof Act of 1868, which made it an offence to sell, offer for sale, transfer, export or pawn an unproofed firearm, with certain exceptions for military organisations. The building was designed by John Horton and consists of a centre bay, emphasised by a segmental parapet, which contains trophies by William Hollins. A Jacobean-style gateway was added in 1883.