Conn's first appointment as a botanist was with the Lae Herbarium in 1974. He then became herbarium curator and a lecturer at the Papua New Guinea Forestry College,
Bulolo (1976–1979). He is a scientific advisor to the Food and Agriculture Organisation. In Australia, he has been senior botanist at the
National Herbarium of Victoria (1982–1987), and botanist (and principal research scientist) at the
National Herbarium of New South Wales (1987–2015). In 1994-1995, he was
Australian Botanical Liaison Officer at Kew. While with the National Herbarium of New South Wales, he managed the
Australia’s Virtual Herbarium Project for New South Wales, and was scientific editor of the journal
Telopea from 2013 to 2015. ==Some published names==