Robert Peel Glanville Blatchford was an English socialist campaigner, journalist, and author in the United Kingdom. He was also noted as a prominent atheist, nationalist and opponent of eugenics. In the early 1920s, after the death of his wife, he turned towards spiritualism.

The Social Democratic Federation (SDF) was established as Britain's first organised socialist political party by H. M. Hyndman, and had its first meeting on 7 June 1881. Those joining the SDF included William Morris, George Lansbury, James Connolly and Eleanor Marx. However, Friedrich Engels, Karl Marx's long-term collaborator, refused to support Hyndman's venture. Many of its early leading members had previously been active in the Manhood Suffrage League.