This series relates to the conveyance of mails by Underground pneumatic tube in London. It comprises reports and papers produced and used by the committee appointed in 1909 by the Postmaster General to consider the introduction of the underground transmission of mails within London and plans of the proposed route for the railway, showing rail levels and junctions. It also contains a copy of the Post Office (London) Railway act and the patent granted to Hosiah Latimer Clark for the invention of apparatus for conveying post by pneumatic tube, (POST 20/30). Papers relating to the construction, maintenance and expansion of the Post Office (London) Railway are also present including specifications, invitations to tender, conditions of contract, estimate of costs and technical plans relating to the construction of new stations, car depots, subways, additions and alterations to stations, including the fitting and maintenance of electrical equipment. This is also demonstrated through numerous plans held within the collection. As well as the Manager's annual reports, there are also numerous files of miscellaneous correspondence, memoranda and reports from the Post Office to various departments and organisations regarding the Post Office (London) Railway, historical accounts. There are also two photograph albums of railway equipment and work being carried out on it.
Some of the plans show properties purchased by the Post Office following the passage of the Post Office (London) Railway Act in 1913. There is a series of signed plans dated 26 October 1914 showing the depth and route of the Post Office (London) railway below ground with details of tunnels, shield chambers, and shafts. There is also a series of plans marking individual and corporate properties along the proposed route of the Post Office Railway.
