In mid-1924, a trapper, Wilson B. Sinclair (1894?–1935), shot some small wallabies that occupied rocky outcrops near Dajarra in north-west Queensland (21o41’S, 139o31’E). He noted an unusual, very marked, pink colouring on the fur around the neck and donated skulls and skins to A. S. Le Souëf, Director of Taronga Park Zoo, Sydney. It was a new species, the Purple-necked Rock-wallaby (Petrogale purpureicollis), but the composition and function of the pigmentation are still not understood. Three museums hold a total of 17 macropod specimens that can be attributed to Sinclair, and he has now been identified as the W.B.S. who was the author of regular Nature Notes in the Cairns Post newspaper from August 1925–May 1928, the first resident nature columnist in Cairns. Many of his Notes included local field observations and he also raised conservation issues, such as the need for reserves and public education on the values of wildlife. Sinclair’s field notes from elsewhere in Queensland suggest that while making his living as a trapper, he had the eye and memory of a naturalist for the wildlife he encountered. Sinclair is the only trapper-naturalist known to have extended his role to nature writing for the Queensland public. However, he also made extravagant, unverifiable claims to have had experience collecting overseas (possibly based on information from contacts in zoos), and service in WWI (possibly based on the experiences of another trapper-naturalist, Benjamin Hore). There are clues to Sinclair’s life and movements from 1924–1935, including through his association with his partner, Kathleen Finn. During the 1930s depression they moved to New South Wales, where Sinclair was unemployed, was convicted of illegal trapping, and died in November 1935. However, Sinclair’s origins (said to be in the USA) and his life prior to 1924 cannot be traced, and his identity remains as mysterious as the pigmentation of the Purple-necked Rock-wallaby.