[1][2] Thomas was elected to the executive of the Amalgamated Miners' Association (AMA) in July 1891 and became president of its Broken Hill branch in 1892.

As a result of his criticism of the magistracy in relation to the arrest of eight fellow committee-members on conspiracy charges, he was dismissed as a Justice of the Peace.

[1] Thomas was elected as the Labor Party member for Alma, covering part of Broken Hill in the Legislative Assembly in 1894,[2] where he campaigned for improvements to workplace health and safety.

[1] Thomas visited England as a member of the Imperial Parliamentary Association in 1916 and was thus absent during Labor's split over conscription.

In 1918 Thomas chaired the select committee on "the effect of intoxicating liquor on soldiers", submitting a dissenting report with senators William Bolton and James Guy that called for the introduction of prohibition.

He sought to increase Senate scrutiny of the government by allowing ministers from the House of Representatives to appear in the chamber (and vice versa), successfully introducing a motion to that effect in 1920.

[4] After politics, Thomas was active as a Methodist preacher opposed to gambling, smoking and drinking and in particular supporting prohibition of alcohol.