He joined the Royal Ulster Constabulary in July 1978 immediately after graduating from QUB and served in all ranks up to Assistant Chief Constable (in the RUC and Police Service of Northern Ireland). After leaving the police service he worked for the EU (for five years as a Head of Mission and as Special Adviser to the Secretary General) and, since then, as a security sector reform consultant for a variety of international agencies in numerous countries. He has published on topics such as police reform and change management, the importance of comprehensive community policing strategies, and, a human rights-based approach to countering violent extremism.