This is not a record of every web page visited, May said: "If someone has visited a social media website it will only show they have accessed that site, not the pages they visited or what they said. It is simply the modern equivalent of an itemized phone bill."
That comparison "was a bit crass," said Mike Weston, CEO of data science consultancy Profusion. "It's more useful and more intrusive. You can tell quite a lot more about what people are looking at online than you can from an itemized phone bill."
But May said there would be further restrictions on what could be stored: Law enforcement agencies will not be allowed to determine whether someone had visited a news website or a mental health website, only whether they had visited a social media website or a communications service, she said.
However, in certain cases the police will be allowed to determine whether someone has visited a particular IP address -- which will allow them in many cases to determine which website they visited.
In preparing the legislation, the government had consulted with ISPs in the U.K. and in the U.S., May said. Whether they are happy with the cost of capturing and storing all that traffic data for the government is unclear.
"There are suggestions that the cost to businesses could be £245 million over ten years," said Weston.
Boasting of the draft bill's provisions for transparency regarding the activities of the security and intelligence services, May said: "There remain some powers that successive governments have considered too sensitive to disclose for fear of revealing our capabilities to those who mean us harm."
But rather than proposing to finally lift the veil on those powers, she plans to give the agencies explicit permission to obtain data in bulk, putting an end to accusations that they conduct such operations illegally.
She proposed regrouping existing surveillance supervisory powers and handing them to a new Investigatory Powers Commissioner who will hold the intelligence agencies to account, and putting a "double lock" on the authorization of interception warrants by requiring approval from government ministers and from a panel of judicial commissioners.
One of the companies that already knows most about our browsing habits, Google, did not respond to a request for comment. Another, Facebook, said it is reviewing the bill and will follow its progress through Parliament.
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