This accession series forms part of the main Navy Office correspondence files series CRS B4883. In 1911 following the expansion of the Naval Board, which was within the Defence Department, the Navy formed a registry separate from the Defence Registry. This registry was based on a single number system and operated until 1921, even though the Navy had been created as a separate entity from Defence in 1915. 

A new multiple number system was implemented in 1922 (CRS B5572); at almost the same time (December 1921) Navy ceased to be a separate Department and was absorbed once more into Defence. The new registry system operated until the end of 1922, then in April 1923 the Navy, in its own registry, was required to change its system by taking a section of the Defence Index and Registration system. Active files from any of the Navy's previous systems were re-registered and top numbered into this new series (CRS B4883). 

The numbering system for Navy files also followed the primary numbers used for Army but with -/201/- onwards as secondary numbers in order to distinguish Navy files from Army files. This Navy series is therefore commonly known as the '201' series. Large gaps are evident in the series due to the fact that in late 1926 Defence central registry took over responsibility for civilian personnel matters, files in relevant subject classes being withdrawn and top-numbered into the Defence correspondence series (CRS A664). This series ran from 1923 to 1950, and was not affected by the formation of the Navy, as once more a department separate from Defence, in 1939. 

With the creation of this independent Department of the Navy, the responsibility for civilian personnel returned to Navy Office and few files were raised with the '201' infix. However, they were maintained as separate series in the Civil Staff Section of the navy registry and were not amalgamated with files in this series. They have been registered as a separate series (CRS B4881). Files relating to Naval personnel matters also apparently came to be maintained as a separate group by Navy Office registry although registered in the same '201' series as the general correspondence files. Files relating to Naval personnel were transferred to Archives still arranged as a separate group and have, therefore been registered as a separate series (CRS B4884). Apart from the standard administrative subjects this series contains records relating to 'Training', 'Personnel/Establishment', 'Defence equipment', 'Acquisition of land for Defence purposes', and 'HMAS' ships. 

During, and immediately after the war, files on many new subjects became necessary. For example, subjects were introduced for 'Rationing' and 'Volunteers' in 1944, and a whole new range introduced for Post-War Reconstruction matters, e.g. 'Demobilisation', 'Re-establishment and Re-employment'. (See CRS B5612, Authorized list of subject headings for correspondence files, multiple number series ('201'series), 1923-1950, for more details). Confidential matters were registered into the series, with only the addition of 'C' to the cover of the file. Documents classified as 'Secret' were registered into a separate series for classified files (CRS B5573). This series came to a close in December 1950 with the introduction of a new registration system in 1951. 

The records in MP139/1 are part of Commonwealth Record Series B4883, correspondence files, multiple number series ('201' series), but have not been physically converted to CRS B4883 They should be requested under the MP139/1 number. This series has also been entered at item level onto RecordSearch.

Other physically unconverted elements of CRS B4883 are MP124/6, MP1049/3, MP151/1, MP1185/9, MP981/1, MP692/1, MP138/1 and MP150/1. 

Administrative information. 

The following data was keyed from the paper documentation: Form number: CA 17 Creating department: Navy, Navy Office, Central Registry Transferring department: Navy, Navy Office, Central Registry Date of transfer: 15/07/1968 Archives file number: RWM31/2/33