In 1976 the GPO (later British Telecom) opened the world's largest international exchange on the site, due to the hold ups in the construction of their new Mondial House, with the "De Havilland" Plessey TXK2 and "Mollison" Ericsson TXK5.
The GPO (later British Telecom) established a global hub at this location in 1976. The construction of their new headquarters, Mondial House, was hindered by delays, prompting the use of the "De Havilland" Plessey TXK2 and "Mollison" Ericsson TXK5.