This is an insider’s history of the UK’s development of on-site inspections for nuclear, chemical, and biological weapons arms control and disarmament treaties from the late 1980s through to the first two decades of the 21st century. It provides for the first time in print a detailed narrative and analytical account from the personal perspective of a senior Foreign and Commonwealth Office expert, who participated in scores of realistic and demanding verification exercises at British as well as overseas military and commercial facilities, including at the former Soviet nuclear weapons test site at Semipalatinsk in Kazakhstan. The book draws on the author’s personal recollections, state papers in The National Archives and official reports submitted to the Conference on Disarmament and other international meetings to pull together a fascinating and riveting account of a key, but hitherto neglected part of Cold War and post-Cold War history. Despite the differences between nuclear, biological, and chemical weapons and their means of production, the UK’s verification exercises recounted in detail here revealed many common lessons applicable to the design and implementation of on-site inspections regardless of treaty. Generally nuclear, chemical and biological arms control verification is discussed separately, but this volume uniquely discuses all three in an overall coherent overview of the lessons learned. In addition to the serious nature of the subject matter, the author also recounts the humour that was ever present and many other tales that never quite made it to the formal reports produced after the exercises.