Director switching device, made by the Automatic Telephone Manufacturing Company, Edge Hill, Liverpool, 1927. From the first London director exchange at Holborn.
The Director telephone system was used in some large cities in Britain from the 1920s to the 1960s. In large areas, calls crossed across the city, so different exchanges needed to be connected. Within the Director area, a switching device routed telephone calls between exchanges that were not in direct communication using a three letter code. The first Director exchange in Europe was opened at 270 High Holborn, London, in 1927.