Ms May insists that there are no privacy concerns here because they're only getting "metadata" -- like "an itemised phone bill" -- and that's not anything you need to worry about. To test out this hypothesis, The Independent filed a Freedom of Information request for her browsing history for the last week of October, 2015. They generously allowed Ms May to redact anything of a national security nature before responding.
After stalling beyond the legal limit, the Home Office rejected the request, calling it "vexatious."
“We have decided that your request is vexatious because it places an unreasonable burden on the department, because it has adopted a scattergun approach and seems solely designed for the purpose of ‘fishing’ for information without any idea of what might be revealed.”
Source: http://boingboing.net/2015/12/28/uk-home-secretary-rejects-requ.html