Legislation governing the collection of communication data by Britain’s eavesdropping agency, GCHQ, is complex, the senior official responsible for its oversight has said .”It is an extremely difficult act of parliament to get your mind round,” said Sir Anthony May, the interception of communications commissioner.
http://www.theguardian.com/uk-news/2014/feb/11/gchq-number-personal-data-intercepts-law-too-many-official