“We don’t believe in leaders,” John McDonnell once said. “We believe that leaders should be following the masses.”

The guiding philosophy of the Labour left has always been that power should reside with party members rather than a political elite at Westminster. Whether they were campaigning for the mandatory reselection of MPs, organising street protests or engaging in direct action, the socialists’ defining purpose was to challenge the establishment and focus on non-parliamentary routes to power. It was their success in winning over members, and recruiting new registered supporters, that enabled them to seize the leadership four years ago.

From the start, Jeremy Corbyn positioned himself as the head of a democratic popular uprising, rather than a top-down autocrat. “We are a social movement,” he