The National Boiler and General Insurance Co Ltd was established in 1894, with an office in St Ann's Square, Manchester. A predecessor company, National Boiler Insurance Co, had been set up in 1864 and operated for 30 years before the change in company name.

The company supplied the National brand fusible plug for high pressure boilers, and also offered insurance and inspection of boilers and kiers, and steam and gas engines, prepared plans and specifications, and carried out testing of engines and boilers. By 1903, insurance and inspection had expanded to cover steam pipes, economisers, dynamos, motors and other electrical plant.

In 1904, the National Boiler and General Insurance Co Ltd entered into a private arrangement with a number of other insurance companies, including the British Engine, Boiler and Electrical Insurance Co.

In the 1920s and 1930s, the company also supplied National brand economiser circulators to improve efficiency of economiser pipes, and National brand safety valves, which it continued to supply into the 1960s.

The company moved from St Ann's Square to St Mary's Parsonage, Manchester, in 1936. The company archive held by the former Greater Manchester County Record Office, now part of Manchester Archives+, ends in 1982, suggesting that the company continued until at least this date.