Martyn first joined the Conservative Primrose League, but while working in Reading she lodged with her maternal aunt, Mrs Bailey, who held pronounced left-wing views. She briefly became a radical and then a socialist. In 1891, she was appointed a governess at the Royal Orphanage Asylum in Wandsworth, London, and joined the London Fabian Society. The following year, ill-health forced her to give up work and she began to devote herself full-time to the socialist cause. However, this was tempered by the devout religious views she had inherited from her parents, and she strongly disagreed with the Marxist principles of many of her contemporaries. For a while, in 1893, she was a sub-editor on the Christian Weekly.