Marconi's Wireless Telegraph Company Ltd. was formed in 1897 as the Wireless Telegraph and Signal Company Ltd., its name changing in 1900. It was originally created to enable Guglielmo Marconi to develop and exploit his innovative work on wireless telegraphy. It was taken over by the English Electric Company Ltd. in 1946, but continued in existence as a separate subsidiary, renamed the Marconi Company Ltd. in 1963. It also retained a substantially separate identity following the merger of English Electric with the General Electric Company in 1968, as GEC-Marconi Electronics Ltd. In 1998 it was reorganised as Marconi Electronic Systems Ltd. and was merged with/sold to British Aerospace the following year, becoming BAE Systems.

To reflect the continuity of Marconi operations throughout these administrative changes, the records of all these companies are considered together rather than being treated as separate entities.