Born in Kilmarnock, Minto left school at the age of 11, and completed an apprenticeship as an engineer, finding work in the shipyards.
He joined the Independent Labour Party (ILP) in 1906, and worked closely with Jimmy Maxton.
[2][3] Minto struggled to find work after the war, and relocated to Leicester in 1919, where he served as secretary of the city's unemployed workers' committee.
He later found work with the Leicester Co-operative Society, and joined the Amalgamated Engineering Union.
[2][3] During the 1930s, Minto was active in the Socialist Sunday School movement and the Left Book Club.