he largest overseas station in the Project P415 network is the US satellite and
communications base at Menwith Hill. near Harrogate in Yorkshire. It is run undercover by
the NSA and taps into all Britain's main national and international communications
networks (New Statesman, 7 August 1980). Although high technology stations such as
Menwith Hill are primarily intended to monitor international communications, according to
US experts their capability can be, and has been, turned inwards on domestic traffic.
Menwith Hill, in particular, has been accused by a former employee of gross corruption and
the monitoring of domestic calls.
The vast international global eavesdropping network has existed since shortly after the
second world war, when the US, Britain, Canada, Australia and New Zealand signed a secret
agreement on signals intelligence, or "sigint". It was anticipated, correctly,
that electronic monitoring of communications signals would continue to be the largest and
most important form of post-war secret intelligence, as it had been through the war.
Although it is impossible for analysts to listen to all but a small fraction of the
billions of telephone calls, and other signals which might contain "significant"
information, a network of monitoring stations in Britain and elsewhere is able to tap all
international and some domestic communications circuits, and sift out messages which sound
interesting. Computers automatically analyse every telex message or data signal, and can
also identify calls to, say, a target telephone number in London, no matter from which
country they originate.
