Henry Bolckow (1806–1878) and John Vaughan (1799–1868) were lifelong business partners, friends, and brothers-in-law. They established what became the largest of all Victorian era iron and steel companies, Bolckow Vaughan, in Middlesbrough. Bolckow brought financial acumen, and Vaughan brought ironmaking and engineering expertise. The two men trusted each other implicitly and "never interfered in the slightest degree with each other's work. Mr. Bolckow had the entire management of the financial department, while Mr. Vaughan as worthily controlled the practical work of the establishment." At its peak the firm was the largest steel producer in Britain, possibly in the world.