Horatio Bryan Donkin was a doctor who started his career in challenging spiritualism which was in vogue at the time. He was physician, psychologist and friend to both Karl Marx and Freidrich Engels. He was appointed Medical Commissioner for Prisons, and took great interest in the psychology of criminals. He successfully opposed Winston Churchill’s proposals to introduce eugenics into Britain. During the First World War he spent time trying to alleviate the problems associated with STDs in soldiers returning from France. Horatio Bryan Donkin was the grandson of Bryan Donkin, a prominent engineer. His father, also Bryan Donkin, worked as an engineer in the family company. He was familiar with some of the people in the Bloomsbury Group.