[2][page needed] Included among the predecessor companies[3] are the following: The immediate history stemmed from the 1968 acquisition of Associated Electrical Industries (AEI) by GEC.

A few weeks thereafter, a merger was agreed between the power and transport businesses of GEC and those of Alsthom of France, part of Compagnie Générale d'Electricité (CGE).

The Alstom Transport factory at Preston was the last site of the former GEC Traction to remain open, albeit on a much reduced scale to that in the 1970s and 1980s.

In June 2017, Alstom announced that the Preston Strand Road site would close and be vacated by June 2018, and operations would be transferred to Alstom's new facility at Widnes (traction equipment engineering and production, and AC motors), terminated (DC motor repair and overhaul) or outsourced (logistics).

Trafford Park, Manchester – OS grid ref: SJ 792 961 Sited on a 127-acre complex to the south of Westinghouse Road and shared with other member companies of the GEC Power Engineering Group, this former Metropolitan Vickers and AEI site had the administrative headquarters of the company as well as manufacturing facilities.

In 1990 (date to be confirmed) the former Low Voltage Switchgear site at Trafford Park (West Works) was renovated to be the new manufacturing facility for GEC Alsthom Traction, with an electronics workshop, machine shop and plating baths and assembly shop for switchgear, equipment cases and power modules.

Attercliffe Common, Sheffield – OS grid ref: SK 389 899 This 9-acre site had specialised in traction rotating machine and gears production since 1923, latterly as an AEI factory before the formation of the company.