The detection of potential terrorists is difficult. A state that upholds the civil and political freedoms of a democratic society cannot know the intentions of all individuals who engage with extremist ideologies, including those leaning towards violent action. So, with limited resources, counter-terrorism agencies have to make tough choices about where to focus their intelligence efforts. Professor Michael Clarke, the former Director-General of the United Kingdom’s Royal United Services Institute, put it this way:

One will be astonished at how little agencies can do, because it takes so much human energy to go down one track. The idea that the state somehow has a huge control centre where it is watching what we do is a complete fantasy. The state and [the Government Communications Headquarters, the United Kingdom’s signals intelligence agency] have astonishingly good capabilities, but it is as if they can shine a rather narrow beam into many areas of cyberspace and absorb what is revealed in that little narrow beam. If they shine it there, they cannot shine it elsewhere.1


Although such detection is difficult, it can be, and often is, achieved and has resulted in the disruption of many proposed terrorist attacks around the world.


For the reasons we have given in Part 6: What Public sector agencies knew about the terrorist, we are satisfied that, leaving aside the email to the Parliamentary Service, there was no information available to the relevant Public sector agencies that could or should have alerted them to the terrorist attack. In Part 8: Assessing the counter-terrorism effort we consider, amongst other issues, why information about the individual’s planning and preparation did not come to the attention of the counter-terrorism agencies.  In this Part, we provide an introduction to that evaluation. Some knowledge of the content discussed in Part 4: The terrorist and Part 6: What Public sector agencies knew about the terrorist is necessary to make sense of this Part. We advise readers to familiarise themselves with those Parts first.