In both theory and practice the SPGB was an extreme manifestation of the pre-1917 Marxist tradition. Its function was to educate the workers in the intractability of capitalism and the hopelessness of all trade union action or reform: its medium was the streetcorner pitch where speakers would harangue passers-by and sell the Socialist Standard . Since prospective members were examined for their knowledge of Marxism and ability to speak in public, and since they prided themselves on their ‘scientific socialism’, propagandists of the SPGB enjoyed a reputation as formidable Marxist purists.