Siemens Plessey was the name given to the Plessey assets acquired by Siemens in 1989. Today most of these units are part of BAE Systems while some units are now part of EADS.
History
Background : before 1989
The history of the evolution of Siemens Plessey division traces to 1988, when the UK regulatory authorities rejected a full merger between the British-based industrial conglomerate - General Electric Company plc (GEC), and the Plessey company - a historic British-based international electronics, defence and telecommunications company founded in 1917. Plessey was at the time the second largest defence electronics contractor to the Ministry of Defence and the largest supplier of traffic control equipment. As a solution, GEC and Plessey merged their communications businesses the same year to form GEC Plessey Telecommunications (GPT).