The emphasis on real-time data could also pose problems for GCHQ's own systems and hinder the work it is trying to do, added Wynn. "Given the enormous number of transactions involved, GCHQ [could] suffer from information overload, trying to sift through millions of calls, emails, texts and web visits to find what they are looking for, rather than analysing patterns in historic data."
The Information Commissioner's Office said it will be keeping close tabs on the Home Office's work in this area.
"The Information Commissioner's role in this Home Office project has been to press for the necessary limitations and safeguards to mitigate the impact on citizens' privacy," the ICO said.
"We will continue to seek assurances [but] ultimately, the decision to proceed with the project is one which has to be taken by Parliament."
