This series contains confidential printed reports, memoranda etc, which were specially printed and given a limited circulation, dealing with all aspects of the administration of the departments and the armed forces.
They were issued from 1853-1858 in a numbered series running continuously from 1853 to 1855 and thereafter in an annual numbered series. In 1859 a prefix (letter O or number nought) was introduced which was used in a single sequence until 1886 when a series with an A prefix was introduced (paper O 1016 was followed by paper A16).
There were also separate B and C series of papers, but the latter (which by the 1940's was reserved for papers classified 'confidential') does not survive as a distinct series.
There were also other serial numbers in use for secret and confidential papers, usually those originating in other departments. Such documents will normally be found in the records of the originating department.
Material originally assigned to WO 130, which was abolished in June 1969, is also in this series.