The Linesman/Mediator Project Authority was set up within the Ministry of Aviation in January 1965 and fell within the Electronics Division. This division was responsible for basic research on, and the development of, radar and other electronic equipment required by the fighting services and civil aviation, and for technical advice on overseas sales of British equipment. This work involved the direction of electronics research and development carried out in experimental establishments and in industry, the preparation and maintenance of inter-services catalogues and the standardization of components.
The Linesman/Mediator Project Authority was established initially on a temporary basis to define Stage II of the Linesman/Mediator Project, with two staff (a director, at air commander level, and his personal assistant), but by November 1965 consisted of a staff of about twenty. Originally answerable to the Director General of Electronics Research and Development (DGLRD), it subsequently became responsible for the whole project under the Linesman/Mediator Steering Committee, answering to the DGLRD on administrative matters only. When the Ministry of Aviation was abolished in February 1967, its research and development functions passed to the Ministry of Technology (MINTECH) where the work on the project continued. In January 1968, the unit's terms of reference were revised to exclude Linesman Stage I.
By January 1969, the air defence aspects of the project were largely well defined and the project authority, in determining the post-stage I requirements, was concerned almost exclusively with the air traffic control aspects of the system. The steering committee decided therefore that the project authority should in future operate within the National Air Traffic Control Service (NATCS), and be directly responsible to CNATS for the air traffic control requirements of the Linesman/Mediator project.
As a consequence, the terms of reference were again redefined, and the Project Authority was transferred out of MINTECH and into the Board of Trade (BOT) with effect from 1 June 1969. At that point it became known as the Directorate of Control (Linesman/Mediator). The Department of Trade and Industry assumed responsibility in 1970. On 27 September 1971 when the Directorate of Data Processing (Air Traffic Services) came into being, and the Directorate of Control (Linesman/Mediator) was disbanded.
The Directorate of Data Processing (Air Traffic Services) was made responsible for all aspects of air traffic services data processing, including those which the Directorate of Control (L/M) and the Directorate of Telecommunications (ATS) had previously held.
The Directorate of Data Processing passed to the Civil Aviation Authority (CAA)on its establishment in April 1972.