Gray’s Inn is one of four Inns of Court in London, the furthest away from the Royal Courts of Justice and the smallest of the four (the other three are Lincoln's Inn, Inner Temple, and Middle Temple). All barristers are affiliated to an Inn of Court.  The majority of the Inn’s buildings are let to barristers and commercial tenants and produce income to fund the Inn’s charitable activities. Hidden amongst the London jungle, on the north side of Holborn, Gray’s Inn has a substantial estate. The exact date of the establishment of the Inn is unknown; however, the earliest reference to it appears in 1370.  Selectaglaze first started work at Gray’s Inn back in 1999, when one of the buildings was being converted to an apartment hotel for use by members. A total of 65 windows were treated with large Series 60 tilt-in vertical sliders, to match the off-set primary single glazing. The units were installed to improve the thermal insulation, as the original glazing was cold and draughty. In 2017 a further 40 units were installed, again to areas used as residential accommodation for barristers and trainees alike. A mixture of Series 10 horizontal sliding units and Series 20 vertical sliding units were installed to provide thermal insulation as well as noise insulation for those apartments overlooking the noisy and busy Gray’s Inn Road. The Estates team are systematically refurbishing key areas of the estate which have been identified as vulnerable and requiring upgrading to bring them up to 21st century standards. With such a high demand for space, the process is not as quick as they would like.