John Brown and Company, steel makers of Atlas Works, was founded in 1838, in Orchard-street, Sheffield by John Brown (1816-1896). In 1844 the firm moved to larger premises on Furnival Street and in 1855 moved his new Atlas Works to Savile-street Brightside in an effort to centralise his workshops and workforce in one place.

In 1848, Brown invented and patented the conical spring buffer for railway coaches, which increased both safety and comfort. His invention made Brown's name and fortune. A few years later he took into partnership Mr J. D. Ellis and Mr W. Bragge. It was about this time the firm began the manufacture of an iron suitable for conversion into steel, and so laid down the foundation of a new Sheffield industry. By 1859 Brown was producing rails for the quickly expanding railway industry using the Bessemer process.

In 1860 Brown built a rolling mill and submitted examples of rolled armour plate to the Royal Navy. Tests on the armour at Portsmouth in 1862 were so successful that by 1867 75% of Royal Navy ships had Brown's armour plate on them. The success of his armour business made Brown a personal and professional fortune. 1864 saw Atlas Works converted into a limited liability company with a capital of £1,000,000.

By 1899 the firm had supplied many component parts of ships; they believed it could gain more value by building the ships themselves together with their propulsion systems. They took over the shipbuilding yard of Clydebank Engineering and Shipbuilding Co‎ of Clydebank. The company acquired seven-eighths of the ordinary shares of the neighbouring Sheffield company Thomas Firth and Sons in 1902 by exchange of shares and entered a working agreement; the companies continued under their own management until they finally merged in 1930 forming Thomas Firth and John Brown, otherwise known as Firth Brown.

In 1955 it was decided that, on denationalization of Thomas Firth and John Brown, individual shareholders should have the opportunity to invest in the shares, rather than them being acquired by John Brown and Co. In 1966 the engineering works were separated from the shipyard by the creation of a new company John Brown Engineering (Clydebank) Ltd while the shipyard continued under the name John Brown & Co (Clydebank) Ltd.