He worked as an orchardist at Clare for a time, before establishing a wheat and wool property "Retreat" at Illabo or Bethungra, New South Wales with his brother George around 1906.

[3][6] He campaigned hard on rural issues, distanced himself from city interests and won in one of the largest upsets in New South Wales history when he defeated the incumbent Premier, Nationalist William Holman, for the third and final seat.

As a Progressive MLA, he was one of the "True Blues" led by (Sir) Michael Bruxner and D. H. Drummond who broke with the party leadership in 1921 to oppose a coalition with the Nationalists for the 1922 election.

[7] The conservatives in New South Wales won a landslide victory in 1932 under Nationalist leader Bertram Stevens, and Main was one of several Country Party MLAs invited to hold portfolios in a new coalition ministry.

In 1938, Main retired to his farm after leaving politics, but continued to be involved in the Country Party, and served on its executive council from 1956 to 1957.