The “impossibilist revolt” in the Social Democratic Federation (SDF) at the turn of the last century led to the formation of two new political parties — the Socialist Labour Party of Great Britain (SLP-GB) in 1903 and the Socialist Party of Great Britain (SPGB) in 1904. In the period up until the outbreak of the First World War, both parties were roughly the same size — each with no more than three hundred members. Yet labor historians have concentrated on the history and theories of the SLP-GB to the almost complete neglect of those of the SPGB, and worse, relegated the latter to a sneering footnote.

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