Originally based at Trafford Park, Manchester, England. Holding company for British Thomson-Houston, Metropolitan Vickers, Edison Swann & Ferguson Pailin. Later, Controls (1949), Birlec (1954), Siemens Brothers (1955), W.T. Henley (1958) and London Electric Wire Company & Smiths (1958) were incorporated. From 1959 AEI symbol replaced individual brand names.