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.