Andrew Charles Bain, son of Thomas Charles John Bain and his wife Johanna Hermina De Smidt, was a civil servant in the Cape Colony. He joined the civil service in April 1881 and worked as a clerk in the colonial secretary's office to 1887. For the next 17 years he filled a variety of administrative posts, including that of assistant magistrate of Grahamstown in 1892-1894. In July 1904 he was apointed civil commissioner and resident magistrate at Calvinia and remained there until 1911.
During 1907 "Mr Andrew Bain" presented to the South African Museum a few fossil fishes from Calvinia, and an "imperfect but important specimen of the Mesosaurus". The latter is a small fossil reptile of Permian age, the oldest reptile found in the Karoo strata, which occurs in the Whitehill Formation of the Ecca Group. Some species of fossil fish occur in the same formation. The Calvinia area is underlain by rocks of the Ecca Group.
After leaving Calvinia Bain served as resident magistrate at Wodehouse (from September 1911), Aliwal North (from April 1912), and Queenstown (from May 1913). He was married to Caroline Bain, with whom he had three daughters and two sons.