 In 1854 he joined the Church Missionary Society (CMS) and attended the Church Missionary Society College, Islington.In 1856 the CMS sent Duncan to the North Pacific coast of Canada, and in 1857 he arrived at the remote Hudson's Bay Company (HBC) fort settlement at Lax Kw'alaams, British Columbia, then part of HBC's New Caledonia district and known as Fort Simpson or Port Simpson.He proselytized among the Tsimshians and learned to speak Tsimshian from Arthur Wellington Clah, a Tsimshian lineage head and HBC employee.