Everything that GCHQ does in the UK is perfectly lawful because it is proportional, reasonable and the tools of surveillance are given a wide scope in law, and the privacy of the citizens are respected, including my most humble self. There is excellent oversight via the Security and Intelligence Committee which is appointed by the prime minister and parliament to be independent and thorough, notwithstanding its most recent Chairman, Lord Rifkind, a most respected, experienced and honorable Scot, with a wide knowledge of terrorism, intelligence and secrey, and who is experienced in lecturing us all in how secure and lawful he was and interested in protecting our human and citizen rights; offering to sell his influence to foreign countries who approached him in the guise of newspaper reporters...or was it the other way about...one never knows these days... :-).
However, as the article suggests, this kind of activity may not lawful in the USA, as a warrant or some kind of lawful permission is required under the Constitution. If the NSA facilities are being used by GCHQ and the information is being shared.
The GCHQ is quite adamant that it does not break UK or US law in terms of surveillance, as the British people are honorable, respect democracy and non-interference in the affairs of other nations. And that there is only lawful and legal co-operation with the USA and the rest of five eyes when it comes to sharing information.
Does anyone know if the NSA, if it is true that it is allowing GCHQ to use its facilities legally or illegally, is either sharing the information, or has some kind of filter on tap to prevent it, or its operatives, or associated organisations from looking at the information...