The External Communications function of the Australian Government was passed from the Prime Ministers Department (CA 12) to the Department of External Affairs [II] (CA 18) by a Prime Ministerial directive dated 21 May 1943. Both departments were then housed in West Block and the two cable sections were amalgamated from 17 May into the External Communications Branch of External Affairs. The Prime Minister directed that, for reasons of security and economy, all overseas cables to and from the Australian Government were to be handled by External Affairs.
Transmission overseas of messages from all departments involved various cyphering methods and a variety of cable lines, including commercial and leased lines. Eventually, most cables were sent on some form of teleprinter.
After decyphering, inward cables were typed onto stencils so that multiple copies could be run off on a spirit duplicator for distribution. Printed copies were duplicated onto pre-printed cable forms which carried a security classification vertically down the right hand side of the page in different coloured inks. After the required number of copies had been run off, the master sheets (as the stencils were called) were filed in chronological/numerical order by bundle. Inward master sheets for 1939-1949 are held as CRS A3195.
Most Australian overseas mission were set up after the end of World War II. By 1950, cable traffic had increased to the point where it was more efficient to keep inward and outward sets of the printed copies in binders by post, in post serial number order. From January 1950, master sheets were kept only for internal administrative use and not as archival records.
Post serial numbering ensured that any gaps in traffic between Canberra and a post would be easily noted. Outward cables from Canberra to each post were numbered sequentially, as well as carrying a message reference number, and post cables sent in response were also numbered sequentially. This number was placed in the centre of the page above the body of the text and was the number generally referred to in subsequent correspondence. Registers linking the post and cable serial number were kept solely for the short term purpose of ensuring that all cables had been received. They carried no other identifying information and have not survived. In some cases, the range of post serial numbers is written on the spine of the binder.
Savingrams (non urgent cable messages sent in off peak time or by diplomatic bag) were filed in a separate run of binders and duplicated onto special forms printed in green. Later, they were known as BB (by bag) cables, ranking lower than Routine Priority (RR).
Until about 1961, incoming cables were registered in large bound volumes (CRS A3642). Entries are chronological and show; from, Post Office reference, inward cable reference, subject, inward cable office number, code used, number of words and previous reference and distribution.
From 1939 until May 1974, incoming cables received serial numbers with an I prefix (for inward). Numbers started from 1 at the beginning of each new calendar year. The introduction of computerisation in 1974 made a radical change to the numbering system. All cable messages henceforth were outward, either from Canberra or from the transmitting post, represented by a bigram (sometime a tetragram). Under the new system, serial numbering for each post was continuous until the number reached 999999, when it cycled back to 1. Rather than disrupt the system of keeping printed cables by year, it was decided to keep cables from January to May with the rest of those for 1974.