In 1889 Westminster became part of the County of London, outside of the jurisdiction of the county of Middlesex. In the division of property between the Middlesex and London county councils, the guildhall at Westminster went to Middlesex in exchange for the Sessions House in Clerkenwell which went to London. In addition to being a facility for dispensing justice, following the implementation of the Local Government Act 1888, which established county councils in every county, the guildhall also became the administrative headquarters and meeting place for Middlesex County Council.[9]
Middlesex county leaders decided, in the context of their increased responsibilities, that the first guildhall was inadequate for their purposes, and a second guildhall, designed by F. H. Pownall in the neo-Tudor style, was constructed on the site in 1893.[10][11]
After the county leaders found that the second guildhall was actually too small, the current and third guildhall, designed by J. S. Gibson, was built between 1906 and 1913.[3] The architectural historian, Nikolaus Pevsner, described the design as "art nouveau gothic style".[12] The design involved a symmetrical main frontage of nine bays facing Parliament Square; the central section of three bays which slightly projected forwards, featured an ornate arched doorway with a segmental arched window spanning the first and second floors and a tower above.[3] A 17th century door, which had originally been part of the Tothill Fields Bridewell prison, was installed in the basement of the building.[3] The building was decorated with medieval-style gargoyles and other architectural sculptures by Henry Charles Fehr.[13]
Following the implementation of the London Government Act 1963, Middlesex County Council and the Middlesex sessions were abolished in 1965, but the guildhall continued to be used by the Greater London Quarter Sessions. After the abolition of the Quarter Sessions in 1972, it was used as a venue of the Crown Court.[14] The guildhall ceased to be operate as a Crown Court following the completion of new courthouses in London such as Harrow Crown Court, Isleworth Crown Court and Knightsbridge Crown Court in the 1980s and 1990s.[15]
After the government chose the Middlesex Guildhall as home for the new Supreme Court, it was realised that a great deal of work was required to renovate the building and adapt it to the new use. Renovation plans were developed by architects Feilden+Mawson LLP, supported by Foster & Partners.[17]
Conservation groups were concerned that the planned conversion would be unsympathetic to such an important historic building. The Middlesex Guildhall is a Grade II* listed building, and the statement of importance by English Heritage classed the three main Court interiors as "unsurpassed by any other courtroom of the period in terms of the quality and completeness of their fittings" on 26 August 2004. The conversion works involved the removal of many of the original fixtures and fittings. Save Britain's Heritage unsuccessfully contested the conversion.[18][19]
