Co-founded in 1879 or 1885 by brothers Bertram Thomas, Eustace Thomas and Frank Thomas, Bertram Thomas Ltd (later Bertram Thomas (Engineers) Ltd), was a light engineering firm based in Hulme, Manchester. The company began by doing wiring jobs in buildings, including Stretford Town Hall. The company made electrical switchgear for the electrical distribution network. They also diversified into other electrical equipment for catering and household equipment, such as kettles. Bertram Thomas developed a patented storage racking system called "Tiltrack".

In 1937 Bertram Thomas was listed as an exhibitor at British Industries Fair. Products included "Tiltrack" Sectional Steel Storage Bins and Adjustable Shelving, Steel Cabinets and Cupboards. Electric Dinner Wagons. Carving Tables, Hot Plates, Plate Warmers. Fixed and Portable Electric Heaters, and Motor Car Pre-heaters.'

In 1939 the business was still a private company. By this point the company was providing switchboards for tramways and light railways around Britain and overseas. In the pre-war years they also manufactured Ring Main and battery switchboards for submarines, but focussed on the railway and Rapid Transit side of the business after 1945.

During the 1950s - 1970s Betram Thomas made DC and AC switchgear for Rapid Transit systems in Toronto, New York, Boston, Cleveland, Chicago, Caracas, and Lisbon, amongst other cities.

By the late 1960s Bertram Thomas (Engineers) Ltd was listed as a subsidiary of Hackbridge and Hewittic Electric Co, which was incorporated in Combined Electrical Manufacturers Ltd. Combined Electrical Manufacturers was later bought by GEC, and Bertram Thomas moved to Trafford Park. Manufacture of DC Switchgear continued there until the early 1990s.