Henry H. Swinny came to the Cape Colony in 1897 and joined the Cape Mounted Rifles from February 1898 to February 1903, when he was transferred to the Forestry Department. After a break in his service from 1 January to 30 April 1904 he was appointed as forester at Qumbu, in the Transkei Consevancy, in October 1904. A year or so later he was transferred to Libode (some 20 km east of Umtata). He left his post in about 1906, but in October 1908 returned to the Forestry Department as a third grade forester and was stationed mainly at Port St Johns, Pondoland, until his retirement in 1916. He leased a farm near the town in 1915 and remained in the region for the rest of his life. During his early years at Port St Johns he collected a considerable number of insects and in 1906/7 sold a small collection of Lepidoptera to the Transvaal Museum, Pretoria.
Swinny was a foundation member of the South African Ornithologists' Union (1904) and of the Entomological Society of South Africa (1937). In 1917-1918 he went on an expedition to Tanzania for the British Museum (Natural History), collecting butterflies, birds and small mammals. The latter were his main interest. In 1922 he bought a small farm near Port St Johns, where he experimented with tropical fruit trees. Plants collected by him went, among others, to the National Herbarium in Pretoria. The plant species Bersama swinnyi was named after him by E.P. Phillips.