Head of Criticality Safety at the Atomic Weapons Establishment for some years; Chairperson of the UK Working Party on Criticality; Member of the Working Group for American National Standard 8.15 - Nuclear Criticality Control of Special Actinide Elements[2] coordinated by the American Nuclear Society; Participant in the International Criticality Safety Benchmark Evaluation Project; Member of Advisory Programme Committees and Technical Programme Committees for several International Conferences on Nuclear Criticality Safety (e.g. International Conference on Nuclear Criticality Safety (ICNC) 1991 - UK, ICNC 2003 - Japan, ICNC 2007 - Russia[3]); Authored or co-authored several published papers on various aspects of criticality safety.