Abstract
Sydney Chalmers Allen was the medical officer at New Plymouth Prison during the 1930s, 1940s, and early 1950s, at a time when the institution was largely set aside for men convicted of having sex with boys and other men. This article examines Allen's approach to the sexual lives of the men under his care. Allen admired the work of well-known English doctor Havelock Ellis, and he put a selection of Ellis's ideas to work at New Plymouth. The article works through some of the philosophical similarities and differences between the two men, and explores how Ellis's ideas were taken up and adapted in New Zealand. The article brings together biography, medical practice, and penological trends in the wider history of homosexuality, and it shows the significance of Allen's work at a time when the segregation of homosexual offenders was rare in the international context.