This chapter analyses Kahn’s activities after his retirement in 1972. The chapter focuses on Kahn’s research programmes and his commitment to defending the Keynesian point of view in debates on inflation and unemployment in Britain and elsewhere. It also examines his role in the controversy between the Old and New Cambridge Schools and his confrontations with British monetarists and trade unions. By reconstructing these events, the chapter illustrates the contrast between Kahn’s non-quantitative Keynesianism and the dominant theoretical approaches of the time, both within the mainstream and among heterodox thinkers. It also explores the various strategies Kahn employed to defend and promote his ideas.