Barnicoat was elected to the first Nelson Provincial Council in August 1853 in the Waimea East electorate. He remained a representative for Waimea East until the end of 1876, i.e. the whole period that the provincial council system was in place. From January 1858, he was the council's second Speaker (succeeding Donald Sinclair) for the council's remaining period. On 23 December 1861, Barnicoat unsuccessfully contested the position of Superintendent of Nelson Province against the incumbent, John Perry Robinson. After Robinson died on 28 January 1865, Barnicoat was acting Superintendent for two months. He was the council's last Deputy Superintendent from July 1875.
