Portcullis House is an office building in Westminster, London, England, that was commissioned in 1992 and opened in 2001 to provide offices for 213 members of the Parliament of the United Kingdom and their staff. The public entrance is on the Embankment. Part of the Parliamentary Estate, the building augments limited space in the Palace of Westminster an…Portcullis House is an office building in Westminster, London, England, that was commissioned in 1992 and opened in 2001 to provide offices for 213 members of the Parliament of the United Kingdom and their staff. The public entrance is on the Embankment. Part of the Parliamentary Estate, the building augments limited space in the Palace of Westminster and surroundings.