Scottish-born physician and Neo-Malthusian. Married (wife's name not identified), at least one daughter. Born to a wealthy Glasgow family, Dunlop, who had long believed in the importance of family limitation among the poor and working classes, joined the Malthusian League in 1910. He soon emerged as one of its most active members eventually serving as treasurer. In an effort to secure support from the eugenics community Dunlop joined the Eugenic Education Society, though he was critical of the groups focus on racial eugenics. Dunlop also played a prominent role in trying to convert physicians to the cause of family limitation. When the League was rent by a conflict between those like H.G. Wells who supported a socialist agenda and those like Charles Vickery Drysdale who did not, Dunlop sided with the classical economic positions of Drysdale. In 1916 when Drysdale entered wartime government service, Dunlop took over many of the duties of League secretary. To insure that his orthodox views would continue to be promulgated by the League, Drysdale also appointed Dunlop as editor of the League's journal, The Malthusian. Dunlop served in this position until 1918 when he was called up for army medical service. Dunlop was named foreign vice-president of the Fifth International Neo-Malthusian and Birth Control Conference organized by Sanger in 1925. Dunlop was introduced to Margaret Sanger by the Drysdales during her 1914-15 exile. A close friend of Marie Stopes, Dunlop was wary of Sanger's early association with British socialists and supported Stopes' efforts to open the first birth control clinic in England.