Old Sessions House, Clerkenwell Green

Building Conservation & Restoration

Built in the style of a Palladian villa, this Grade II* listed building required London Stone Conservation to deliver an extensive programme to restore the building to its original design.  Following our work, this historic landmark can now reopen as public and private space.

The building was constructed as the Middlesex Sessions House in 1779 to the design of Thomas Rogers, it was remodelled and enlarged by Frederick Hyde Pownall in 1860. After it closed as a courthouse in 1920, the building was in use as a manufacturing headquarters, a conference centre and most recently as home of the Freemasons. Much of the building, including the main courtroom, had been carved up and remodelled over the years to incorporate offices and meeting rooms, drastically changing the authentic aesthetic and design of the building.

London Stone Conservation started work at Old Sessions House in February 2015 having been awarded the two-year project to fully restore both the interior and exterior stonework. The building had suffered through brutal remodelling, disrepair, unsympathetic restoration works, and severe staining and deterioration to the exterior. Working alongside the client, main contractor, building historians and architects, London Stone Conservation helped to devise a sympathetic repair program with the intention of returning the building to its original design.

This extensive program of work encompassed the restoration of the main courtroom’s Corinthian columns; cleaning and repair of the four original internal stone staircases; conservation of the pediment frieze’s; the full façade cleaning and repair and the addition of a new masonry wall and boundary. The cleaning of the Portland stone façade was a particular challenge, as the build-up of carbon staining and sulphation had resulted in an extremely uneven appearance and therefore the need for multiple sympathetic cleaning methods. Different poultices were mixed and suspended in clay to create a uniform appearance. This non-aqueous form of cleaning also avoided any unnecessary saturation of the stonework, which had been found to mobilise the natural mineral content in the stone causing heavy iron staining.