Grace's Guide is the leading source of historical information on industry and manufacturing in Britain. This web publication contains 138,150 pages of information and 223,038 images on early companies, their products and the people who designed and built them.
of St. Albans.
1936 Private company.
1946 The holding of Cable and Wireless in Marconi's Wireless Telegraph Co was acquired by English Electric Co. As well as the whole of the share capital in Marconi's Wireless Telegraph Co, this also gave English Electric the entirety of Marconi Instruments Ltd.
1961 Manufacturers and designers of telecommunication measurement equipment, industrial electronic instruments, industrial X-Ray apparatus, diagnostic and therapeutic X-Ray apparatus and electro-medical equipment. 1,500 employees. 
1968 GEC acquired English Electric
1974 Marconi Instruments developed a spectrum analyser MI TF2370.