Dubery worked as a postman and became active in the Fawcett Association.
He was also prominent in the Independent Labour Party (ILP), serving on its National Administrative Committee as the representative for London.
[1] Within the ILP, he was part of a minority which supported the UK's involvement in World War I, although he opposed conscription.
[2][3] Despite this, he remained a prominent figure in the party throughout the war, and was one of its delegates to the Allied Socialist Conference held in London in 1917.
In 1921, he resigned from his trade union posts, but continued with the NAEE on a salary of £1000 per year, promoting the resolution of labour disputes without industrial action.