He joined the Christian Brothers and served at Ballarat Vic 3350, Brisbane in Qld and Sydney of NSW. Appointed headmaster to Perth, Western Australia in 1897 he stayed until 1907 then re-appointed in 1912 he served again 1913-1921 Nunan was one of the pioneering Christian Brothers who taught at
Christian Brothers School,
Dunedin from 1876 until 1883. He arrived in Dunedin eight months after the foundation Christian Brothers community led by Brother Fursey Bodkin. Nunan was an influential headmaster of
Christian Brothers College, Perth, where he served from 1897–1908, 1912–1918 and 1920-21. He was one of the four headmasters who inaugurated the
Public Schools Association in
Western Australia. He was a member of the
Royal commission that established the
University of Western Australia. He was also headmaster of
St Patrick's College, Ballarat 1910-1912. A boarding house at
Aquinas College, Perth was named Nunan Residence in recognition of his work at Christian Brothers College, Perth. == Further reading ==