In 1875, Thomas emigrated to Western Australia to take up the positions of Director of Public Works, Government Engineer and Commissioner of Railways. In 1878 he was Commissioner for Western Australia for the Exposition Universelle in Paris. At some point thereafter he travelled to England for health reasons. In July 1883, the Western Australian Legislative Council amended its membership to include the Director of Public Works as an official nominee member. Accordingly, Thomas was appointed to the Legislative Council.