The Ferranti Instrument Department goes back to 1905 and the Scheme of Reconstruction that created the 'New Company' in that year. The department manufactured a wide variety of products ranging from viscometers through to clip-on anometers and until 1921 the Transformer Department was included within the department. Throughout its life the department often acted as a test bed for new products developed by the company, e.g. electronics, before those products were transferred to other departments.

From 1937-1970 the Fuze Department formed part of the Instrument Department and in 1955 the Aircraft Equipment Department was formed and added to the department. After the Radio Department closed down in 1958 the service section of that department was added to the Instrument Department.

In 1974 a new Instrumentation Division was created incorporating the old Instrument Department, together with the Meter and Foundry Departments. In 1978 the Instrumentation Division was restructured becoming Ferranti Instrumentation Limited, incorporating the Weapons Equipment Department, the Aircraft Equipment Department, the Naval Department and Mitchell Hydraulics Division. This same reorganisation also saw the creation of Ferranti Computer Systems Ltd and Ferranti Electronics Ltd.

Subsidiary Companies of Ferranti Instrumentation included Ferranti Measurements Limited (1978-1985), Ferranti GTE Limited (becoming in 1981 Ferranti Business Communications Limited) and Ferranti Resin Limited.

Ferranti Instrumentation Ltd was ultimately dissolved, with some assets sold to GEC-Marconi and Ravenfield Designs.