In the wake of growing public concern in Europe about the telecommunications spying going on through the UK/USA alliance sites, the European Parliament's Scientific and Technical Options Assessment Program Office ordered a report on just what the NSA and Britain's GCHQ were doing at facilities like Menwith Hill and the various sites around the world, including Australia. They turned to Duncan Campbell, who has painstakingly pieced together much of the information that's available on the UK/USA alliance from public sources, over nearly 20 years of research. Duncan Campbell's report on interception capabilities, including a review of UK/USA's telecommunications interception abilities, was written for the European Parliament in May of 1999.
This is by far the most authoritative document ever prepared on just what snooping is being done into your and my telecommunications.
The STOA Report written by Campbell is available at: Link to STOA Report
New Scientist Magazine's report from 15 May on this report is available at: Link to New Scientist Magazine