Dr. John R Walker was Head of the Foreign and Commonwealth Office’s Arms Control and Disarmament Research Unit (ACDRU) from December 2014 to May 2020 when he retired from the FCO. He joined ACDRU in March 1985. John’s main focus was on the Biological and Toxin Weapons Convention (BTWC), the Chemical Weapons Convention (CWC), the Comprehensive Nuclear Test Ban Treaty (CTBT), and the UN Secretary-General’s Mechanism for investigating allegations of CBW use. He was a member of the UK’s Chemical Weapons Convention Steering Group and its Technical Sub-Group during the negotiations and represented the UK during the Preparatory Commission’s Working Group B Expert Groups on verification issues. In addition, his work also included UK nuclear weapons and arms control history and nuclear disarmament verification. He is currently a Senior Associate Fellow at the European Leadership Network and a Senior Associate Fellow at the Royal United Services Institute.