Crispian began his policing career as a constable in London, served as a chief officer in Glasgow, and then as Chief Constable of Northumbria for seven years. Since 2010, he has served the Cambridge University Police Executive Programme as a supervisor of studies by mid-career police leaders. His work with evidence-based policing dates to 2001, when he joined a partnership of English agencies testing restorative justice conferences in multiple randomised controlled trials.