ABSTRACT
Dr Klaus Emil Julius Fuchs is perhaps one of the most important spies the Soviet Union ever had. It has been confidently estimated that his information expedite the Soviet atomic bomb programme by 1-2 years, and more recently his hitherto unknown yet signif cant contribution to their hydrogen bomb programme has also begun to emerge. 1 In early 1950, Fuchs was arrested by British authorities for passing information to the Soviet Union. Sir Michael Perrin, at this time the Deputy Controller for Atomic Energy within the Ministry of Supply, was the scientist tasked with interviewing Fuchs. Perrin was chosen for two reasons: he had been involved in atomic intelligence matters since the war and so had the highest levels of clearance; and in addition he had the technical knowledge to assess Fuchs’s contribution. Following his admission of guilt, Fuchs was interviewed by Perrin in January and again in March 1950.
