John G. Chaplin was a bookkeeper in Port Elizabeth around 1890. He became a member of the Eastern Province Naturalists Society (founded at Port Elizabeth in January 1882 and active to 1923) on 23 February 1882, was elected a member of its management committee in January 1888, became honorary treasurer in January 1889, and was re-elected to this position for the following two years. At a meeting on 6 December 1889 he exhibited some British shells. In 1905 he donated a collection of local and foreign shells, representing 126 species, to the Port Elizabeth Museum.
Chaplin died in 1917. The next year a collection of his poems, Stray verses by a bruised reed (Port Elizabeth, 1918) appeared. The poems were written from 1878 onwards, mainly, it seems, in Port Elizabeth.