This iconic Grade II* Listed building served as the home of the British Government for 64 years, in the form of the London County Council, and later the GLC (Greater London Council) and ILEA (Inner London Education Authority). Shortly after acquiring the lease for the south section of the fourth floor, ‘etc.venues’ appointed Synergy Architects and Jestico & Whiles as executive and design architects respectively.   Synergy Architects turned to Selectaglaze, to install thermal and acoustic efficient secondary glazing, except where there were dado rails, which the conservation officer was keen to retain. As there were no rising ducts of a satisfactory size, air needed to be supplied and extracted through the existing windows. Only windows facing onto the light well or the courtyards could be used and subsequently the top panes of most of the windows facing into the light wells were boxed in and used for ventilation openings. Secondary glazing was therefore only required to the lower part of these windows. Main contractor KPS Partnership Ltd arranged some trial units which proved successful. Thereafter, a total of 148 secondary glazing units were installed, which were a combination of horizontal sliders and lift-out units. Those units exceeding 1600mm high were fit with a 6mm toughened low-E glass. A minimum glass to glass cavity of 150mm allowed for optimal noise reduction.   Since this project was completed the Series 30 has been superceeded by the Series 31 lift-out.