McLaren revisited Melbourne periodically, lecturing on the relationship between body and mind in 1927, publishing a paper in the Australasian Journal of Psychology and Philosophy in 1928, and lecturing for the Melbourne University Student Christian Movement in 1934. He was a prolific journal contributor on medical issues and also discussed the Shinto shrine issue in religious journals. He argued against emperor-worship in Japan in the 1930s and was imprisoned for eleven weeks at the outbreak of World War II before being interned and returned to Melbourne in November 1942. He published Preface to Peace with Japan, Eleven Weeks in a Japanese Prison Cell and They Kept the Faith in the 1943–44 period and later published Christianity, Communism and the World Situation in 1952.
