South Australian stamp overprints
The colony of South Australia began issuing postage stamps in 1855, and continued until the first stamps of the Australian Commonwealth were issued in 1913. Many of these stamps were intended for use on official mail by government departments, and were overprinted with various initials to prevent unofficial usage by staff and to identify the department concerned. The overprints were in use from 1 April 1868 until 1874, when they were replaced by the letters "O.S." which was then used on official mail of South Australia. Red and black were the most common colours for overprints, but blue was also used. List of overprints The initials and the relevant departments were: A. Architect A.G. Attorney General A.O. Audit Office B.D. Barracks Department B.G. Botanical Gardens B.M. Bench of Magistrates C. Customs C.D. Convict Department C.L. Crown Lands C.O. Commissariat Office C.P. Commissioner of Police C.S. Chief Secretary C.Sgn. Colonial Surgeon D.B. Destitute Board D.R Deeds Registration E. Engineer E.B. Education Board G.F. Gold Fields G.P. Government Printer G.S. Government Storekeeper G.T. Goolwa Tramway H. Hospitals H.A. House of Assembly I.A. Immigration Agent I.E. Intestate Estates I.S. Inspector of Sheep L.A. Lunatic Asylum L.C. Legislative Council L.L. Legislative Librarian L.T. Land