Born in Coleorton in Leicestershire, Stewart's father died when he was two years old, and he began working underground in a coal mine, illegally, at the age of eight.
The mine had a local trade union, a remnant of the Derbyshire and Nottinghamshire Miners' Association, and Stewart became active in it.
[1] In 1880, Stewart was elected checkweighman at Annesley, and he was a leading figure in the establishment of a new Nottinghamshire Miners' Association (NMA).
He was elected as its secretary in 1884, serving part-time, but was unable to make progress in recruiting members, and stood aside in 1886.
In 1897, he was again elected as secretary of the union, and also sat on the executive of the Miners' Federation of Great Britain.