Nasty little end run around the law, isn't it?
So how did Echelon fit in with the legal obligation to get warrants for surveillance? The spooks found ways around the law. GCHQ is not allowed to spy on Brits nor the NSA on Americans, so the agencies simply spied on each other's citizens and handed the intel over outside the target country. Thus the two agencies have been outside the law for decades.
So back at MI5's secret info-auction, what exactly did Stephen Lander mean by his 'open society'?. 'Open' not to the public who pay his wages but to anyone with big enough bags of cash.
Steve Boggan's revelation received virtually no follow-up press because it re-opened a can of worms considered too indigestible in London's newsrooms. The creeping privatisation of MI5 was in progress, and who dared to contemplate where that might lead? Lander failed to recognise that the NATO powers can only rely on their spooks keeping mum if they stay on the angels' side of right and wrong, and he had crossed the line.
https://www.rt.com/op-edge/prism-wartime-sell-secrets-604/There have been other sources and books that talk about this over the years....