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Home > Reviews > Lone-Actor Terrorists

Lone-Actor Terrorists

Author Paul Gill

ISBN No 9781138221796

Review date 19/06/2019

No of pages 192

Publisher Routledge

Publisher URL

Year of publication 21/02/2017


Lone-Actor Terrorists: A behavioural analysis. Paperback, by Paul Gill.

Our Review


£ 28

In the very first paragraph of this study of 'Lone Actors', people of all backgrounds and skin colours who have for all sorts of reasons gone on to commit acts of terror, Paul Gill plainly, to the point of coldness, sets out what Anders Breivik did on the afternoon he killed scores of people (and injured many more). Also shocking from the reviewing point of view was a basic grammatical error, all the more surprising because such lapses did not happen further in the book.

Such a mistake, though only human, can grate and the book then had to be good to recover the reviewer's good will. The book does succeed, partly because the subject matter is so gripping. Who are these people who - while outwardly reasonable and law-abiding, until they commit harm, and are caught - break conventions and common human decency? Why do they do it; what on earth are they hoping to achieve? It makes little sense, also because so many of them are caught and imprisoned, or killed. Society can at best only hazard that these people do not abide by the same assumptions that the rest do.

Hence the book, an effort to understand - and hence the backers of the book are, as the author makes no secret, among others the UK Home Office and the US federal Department of Homeland Security. The counter-terrorism policy imperative, we can assume, is: if these lone actors have something in common, or something different from the norm, or some trigger that prompts them to go beyond the boundaries of decency - the authorities can use that insight, to prevent or mitigate further outrages.

Does Paul Gill succeed? If only there were as in crime generally a 'silver bullet', or a bullet of any make of metal. But we can at least say that this academic work could easily have got bogged down in theory and what this and that expert has said in print. Gill is wise enough to resist that, although as he says early on, 'the field has lacked data'. He shows himself well read in what has been said already, and to limit himself to the empirical facts. That could lead to a mash of things that don't really have on the face of it much in common with each other - besides Breivik, and the American bomber Timothy McVeigh, the woman who stabbed the Labour MP Stephen Timms in 2010. Gill's work is up to date enough to include the murder of Lee Rigby, but not Labour MP Jo Cox. They may choose their time and place carefully, but may or may not expect to escape. But, Gill does suggest that the lone-actors encounter a 'large number of roadblocks and hurdles', which may cause them to scale down their ambitious plan (such as size of bombs, or number of targets).

While as he puts it lone-actor terrorism is 'still a black-swan type event' - by definition, not what you'd expect - because the deeds of lone-actors are so extreme and rare, and thus newsworthy, there is relatively plentiful detail to go on. He asks the pertinent questions - is there anything that sets lone-actors apart from terrorists who join or form groups; by age, or education. Do they have a criminal record; what turns them to violence; do they give signs of what they turn out to do ('attack signalling'). Do they learn from other lone actors, although surely that blurs the difference between being a loner and in a group (physical or online). But Gill does find that the 'true loners are few and far between', whether they read an online 'call to arms' or pick up tips from someone or somewhere (the internet).

One striking feature of the known stories of lone-actors is that they aren't necessarily good at their 'tradecraft', such as making or planting bombs. You might expect they aren't practiced in leaving a bomb in the best place - from their twisted point of view, to kill as many people by time of day or place. But not all are as chillingly effective, in a sustained way, as Breivik. Gill devotes a chapter to whether lone-actors are mentally ill - which indeed makes no difference from a counter-terror or site security point of view, but does from a public policy viewpoint, if more resources have to be directed into mental health, or directed in a different way. Here is one way that Gill and others can helpfully find differences between lone-actors; the extreme right wingers who try to bomb mosques and al-Qaeda radicalised people who incite online to take a knife to soldiers in uniform or clergy, or who actually carry it out, may not be motivated the same as other lone-actors who do atrocious things in the name of a single issue (such as hatred of homosexuals) rather than a political or religious world view. In other words, we cannot lump them altogether as nuts, or as anything.

Gill sums up hat 'while mental illness may play a key role in an individual trajectory towards lone-actor terrorism,' and giving the example of a young man who tried to bomb a restaurant in Exeter, 'it can only ever be treated as one distal risk factor that needs to interact' with more factors, including finding a target that the lone-actor feels he or she can take on.

Gill has a chapter on situational crime prevention, suggesting that 'SCP approaches look to squeeze the opportunities of potential even further," given that the lone-actor cannot call on the finance, logistics and know-how of a group. As there are points where everyday people may come into contact with the lone-actor and feel something is suspicious - a bomber has an oddly large number of layers of clothing on a warm day, or is buying things in strange amounts, or making a smell in his lodgings - there are things society might usefully do, from promoting fake bomb-making recipes to encouraging media outlets to pass on to police (but which office or person?) extremist letters, and encouraging shop staff to report suspicious sales, to 'target hardening' of sites.

He ends with a depressing thought; the Woolwich murderers of Lee Rigby got what they wanted - a successful attack, and publicity for their speeches ('television stations couldn't beam the images quick enough'). How do you contain that? The author doesn't have an answer.

A creditable and readable study of an important subject; recommended.

About the author

Paul Gill is a lecturer, in the Department of Security and Crime Science, at University College London (UCL).

Visit to read online the first 20 pages.


1. Introduction 2. Who are the Lone-Actor Terrorists? 3. The Behavioural Underpinnings of Lone-Actor Terrorism 4. Why Go It Alone? 5. The Role of the Internet 6. Mental Illness and Lone-Actor Terrorism 7. Comparing Lone-Actor Terrorists 8. A Situational Crime Prevention Approach 9. Lone Actor Terrorist Dilemmas.