Eric Hobsbawm writes:
Lenin’s ‘vanguard party’ of Marxist cadres, disciplined and ideally full-time, his ‘professional revolutionaries’, was the most formidable political invention of the 20th century. Its impact on the history of that century was extraordinary. Some thirty years after Lenin arrived at the Finland Station, parties of this type ruled over one third of the world’s population. By dint of following the Leninist model, small groups were able to punch far above their weight, while in the right historical circumstances, their structure afforded them enormous potential for expansion and, indeed, state-building. Even in unfavourable conditions, such as those that prevailed in Britain, their impact was out of proportion to their size.