 He was a most vigorous minister and was responsible for a great development of the tramway system, for the building of many new railways, and for many other public works in connexion with water-supply, roads, rivers, harbours and buildings, including the new Sydney railway station.According to "The Bulletin", his sketch for it has "all the salient features of the Colosseum, St Paul's, the Kremlin and a Yankee skyscraper".O'Sullivan held office for a few weeks in the Waddell ministry in 1904 as Secretary for Lands, but possibly from failing health was less prominent in politics win his later years.