The roots of this book lie in a chance encounter back in December 2018, when the authors met in London at an event commemorating the 18th anniversary of the death of Damilola Taylor. As the event drew to a close, we spoke briefly and arranged to spend an afternoon together at Hackney Quest, the youth centre where Luke has worked since 2016. That afternoon, we discussed a range of topics, including the work of the cross-party parliamentary Youth Violence Commission, on which Keir was lead criminologist, and which Luke would later join as co-author of its final report.

Since then, we have worked together closely, not only on this book, but writing journal articles, book chapters and blogs, attending academic and practitioner conferences and, most latterly, on a three-year ESRC-funded project exploring public health approaches to violence reduction. Daily and varied contact over e-mail, phone, Zoom and WhatsApp has resulted in our becoming close friends as much as we are colleagues. We now share as many photos and videos of our own children as we do messages about our work and research.

The relationship we have developed has enabled us to have open and frank conversations about often very difficult and sensitive topics. While our views converge on a great many things, there have also been periods of (in)tense disagreement – we’ve included a footnote in Chapter 2 which summarizes our argument about the value of virtue ethics, for instance. These disagreements could of course have been avoided had we chosen to write separately. However, we believe this book has benefited in numerous ways from the bringing together of two rather different perspectives – one from someone who has worked primarily as a youth worker, and one from someone who has worked primarily as an academic researcher. In part, such benefit lies in what we hope will be the bookߣs broad appeal, to an intended audience that includes practitioners, policy makers and academics. The book reflects a degree of both professional and academic knowledge and experience that it would have lacked were either of us to have approached the task of writing it alone.