This article challenges the militant and industrial unionist version of British coal mining trade union history, surrounding the Miners' Federation of Great Britain and the National Union of Mineworkers, by considering, for the first time, the case of the colliery deputies' trade union. Their national Federation was formed in 1910, and aimed to represent the three branches of coal mining supervisory management: the deputy (or fireman, or examiner), overman and shotfirer. First, the article discusses the treatment of moderate and craft traditions in British coal mining historiography. Second, it shows how the position of deputy was defined by changes in the underground labour process and the legal regulation of the industry. Third, it traces the history of deputies' union organization up until nationalization in 1947, and the formation of the National Association of Colliery Overmen, Deputies and Shotfirers (NACODS). The article concludes that the deputies represent a mainstream tradition of craft/professional identity and industrial moderation, in both the coal industry and the wider labour movement.