The records of the Commonwealth Telecommunications Organisation reflect the history of Commonwealth co-operation in the field of international telecommunications. The collection is arranged into five general classes:

1. Imperial Communications Advisory Committee, 1928-1945
2. Commonwealth Communications Council, 1944-1949
3. Commonwealth Telecommunications Board, 1949-1969
4. Commonwealth Telecommunications Organisation (CTO), Commonwealth Telecommunications Council (CTC), and Commonwealth Telecommunications Bureau, 1966-1987
5. Commonwealth Telecommunications Organisation (CTO), Commonwealth Telecommunications Bureau and the Commonwealth Telecommunications Council (CTC) after 1987
   Each class represents the surviving records of the body that administered Commonwealth telecommunications relations during a particular period. Within each class, the material falls into three broad categories: the annual reports of the administrative body; the minutes, proceedings and memoranda of that body; the proceedings and minutes of committees and subcommittees appointed by the body. Most of this material is collected, by year, into bound volumes. In addition, the collection contains material (in files and bound volumes) that was not generated by the incumbent administrative body, but does relate to Commonwealth telecommunications during the lifetime of that institution and was presumably retained for use in the course of its activities or for reference purposes. Much of this material relates to the reports and proceedings of the Commonwealth Telecommunication Conferences under whose authority the administrative body derived its mandate. In each class, this material is listed under the heading General Documents.

Correspondence, comprising a private letter book 1863-1867, and correspondence and reports relating to the laying of the West Indies cable 1869-1870. The private letter book contains bound letters refering to cable laying in India, the West Indies and Brazil, resistance testing to find faults on cables in a long letter to Fleeming Jenkin, mining companies with which Bright was involved, the Steam Engine Improvement Company and the Railway Lubricating Company. The volume contains many blank pages and some pages have been cut out. Some letters are illegible because of the very faint copy, and there appears to be a double impression on some pages suggesting that a second letter may have been copied onto the same page. The loose correspondence relates to the setting up of the West India and Panama Telegraph Company and includes reports and correspondence concerning the laying of the cable. Some of the papers were used in a court case in 1872 between the West India and Panama Telegraph Company and the India Rubber Company for failing in their contractual obligations.

Papers of the Telegraph Construction and Maintenance Company Limited. The main series consist of contracts including for the supply, laying and repair of cables (TCM/6), cable engineers' logbooks (TCM/8) and ships' logbooks (TCM/10). Other records include memorandum and articles of association 1964-1920, papers relating to the SS GREAT EASTERN and the first Atlantic cables, publicity material and books and pamphlets. The collection also contains records of the Gutta Percha Company, H W Jewesbury and Company and personal papers of Willoughby Smith.

Records of the Globe Telegraph and Trust Company Limited, with records of predecessor and subsidiary organisations as listed below. The records include: minutes and papers presented at meetings, annual reports, constitutional documents, deeds, reports, financial records, administrative files, staff magazines and histories. Deeds which survive from 1717 pre-date the establishment of the business.

Predecessor/subsidiary companies with records in this collection:
Globe Telegraph and Trust Co Ltd;
Aberdeen, Ceylon and Eastern Trust Ltd;
Aberdeen, Edinburgh and London Trust Ltd;
African Direct Telegraph Co Ltd;
Associated Cable Companies;
British Australian Telegraph Co Ltd;
British Indian Extension Telegraph Co Ltd;
British Indian Submarine Telegraph Co Ltd;
Cable and Wireless (Holding) Ltd;
Cable and Wireless Ltd;
Cables Investment Trust Ltd;
China Submarine Telegraph Co Ltd;
Companhia Telegrafica Platino Brasileira;
Connaught Trust Ltd;
Deutsche See Telegraphen Gesellschaft;
Direct Spanish Telegraph Co Ltd;
Eastern and South African Telegraph Co Ltd;
Eastern Extension, Australasia and China Telegraph Co Ltd;
Eastern Telegraph Co Ltd;
Electra House Ltd;
Europe and Azores Telegraph Co Ltd;
Falmouth, Gibraltar and Malta Telegraph Co Ltd;
Great Western Telegraph Co Ltd;
Marseilles, Algiers and Malta Telegraph Co Ltd;
Mediterranean Extension Telegraph Co Ltd;
Pacific and European Telegraph Co Ltd;
River Plate Telegraph Co Ltd;
Share Investment Trust;
Victoria Embankment Properties Ltd;
West African Telegraph Co Ltd.