Alterations and extensions to existing building including: demolition at mezzanine and fourth floor; removal of modern additions at basement, ground, first, second and third floor; construction of six-storey rear extension above ground floor level to provide an increase in office (Use Class E) floorspace. Internal refurbishment and alterations to layout; demolition of listed building at mezzanine level and fourth floor; partial demolition of listed building including removal of modern additions at basement, ground, first, second and third floor; construction of six-storey above ground floor level rear extension.