
Entryism re-entered Labour’s lexicon in the summer of 2015 as thousands of members and supporters of other parties (among them Greens, Trotskyists and Tories) sought to vote in the leadership election. But the term historically refers to a far greater degree of strategy and organisation.
The founding example of entryism was provided by Leon Trotsky and the “French turn”. In 1934, the Russian revolutionary persuaded his supporters to dissolve the Communist League into the Socialist Party in order to maximise their influence. The term has since been applied to any group that enters a larger organisation with the intention of subverting its policies and objectives.