The category A-listed Town Hall in Lerwick dates from 1883 and is the most important civic building in Shetland. GRAS were commissioned to carry out an ambitious £1.2 million restoration and repair package incorporating the conservation and protection of a nationally significant collection of secular stained glass windows, designed and created by several of the leading makers of the time. The stained glass windows in the building had suffered for many years due to the harsh salt-laden environment; and although efforts had been made over the years to conserve them by applying external flexible polycarbonate sheeting, it had not been enough to sufficiently protect the historic glass.

Following extensive research and testing, GRAS with Cannon MacInnes designed a newly-patented non-ferrous isothermal glazing system which isolates the historic glass from the external environment while providing full adjustability and accessibility for maintenance. Comprehensive fabric repairs were also carried out, including grouting of external walls, extensive replacement of defective stone masonry and renewal of leadwork. These technical improvements, combined with the installation of sensitive interpretation have opened up the building to the public, increased the number of visitors to the area and greatly enhanced the long-term prospects for the building.