Barr & Stroud was founded in 1888 by Professor Archibald Barr of Glasgow University and William Stroud of Leeds University, to develop a single observer range-finder for the Admiralty and War Office. By 1904, 100 men were working for the company in a new purpose-built factory near Glasgow.
With the onset of WWII Barr & Stroud focused its drive on military devices. Its workforce rose from 2000 to 6000 between 1939 and 1944 when it made 30,000 range-finders, 150,000 gun sights and bomb sights. It also made 2000 pairs of binoculars per month. After the war, the company developed new equipment for Britain's armed services. In later decades it supplied laser rangefinders for tanks and supplied advanced electro-optics for the guidance system in British Aerospace's Rapier missile project. It also developed thermal imaging equipment for Britain's Swingfire missile system, and supplied Thermal Observation Gunnery Sighting Systems for tanks.
In 1977 they were taken over by the Pilkington Group. In 1992 operations moved from the original factory in Anniesland to a new plant in Linthouse on the site of the former Alexander Stephen and Sons shipyard. In 2000 the company became a subsidiary of the French company, Thales Group, and in 2001 Barr & Stroud Ltd became Thales Optronics Ltd.