The Socialist Labour Party and the Socialist Party of Great Britain came into existence as the result of the “impossibilist revolt” of 1900–1904. The “revolt” was a movement of a few hundred socialists within the Social Democratic Federation, itself a social revolutionary party with a membership of only a few thousands. The absence of widespread support for any of these revolutionary movements in a country whose political tradition has remained predominantly constitutional accounts for the fact that the crisis inside the S.D.F., and with it the origins of the S.L.P. and the S.P.G.B. themselves have been consigned to obscurity in the history of British Socialism.