Hawker Siddeley was a group of British manufacturing companies engaged in aircraft production. Hawker Siddeley combined the legacies of several British aircraft manufacturers, emerging through a series of mergers and acquisitions as one of only two such major British companies in the 1960s. In 1977, Hawker Siddeley became a founding component of the nationalised British Aerospace (BAe). Hawker Siddeley also operated in other industrial markets, such as locomotive building (through its ownership of Brush Traction) and diesel engine manufacture (through its ownership of Lister Petter). The company was once a constituent of the FTSE 100 Index.