The election of Jeremy Corbyn to head the Labour Party represents a sharp turn to the left for the opposition in Britain, the return of the "Old Labour Party" that predated Tony Blair as prime minister and the polarization of politics in the United Kingdom. The vote reflected a sense that Labour had lost its way — like other left-leaning parties in industrialized democracies — a sentiment that was magnified by new procedures for the vote. It is by no means clear that new "old Labour" will be successful in future elections, but Corbyn's rise to power is a manifestation of a deep unease that animates large segments of the voting population, a tendency that can produce more extreme — but not necessarily extremist — candidates on the right and the left.

Following the Conservative Party's surprise win in parliamentary elections earlier this year, then-Labour Party head Edward Milliband stepped down to take responsibility for the loss. The race to replace him originally included three candidates, all anchored in the center of the party and proud supporters of the New Labour platform that had been articulated by Blair and which propelled him and his successor, Gordon Brown, into the prime minister's office for 13 years.

At the last minute — literally — Corbyn entered the race, offering a decidedly different perspective on politics and priorities. His thinking most closely resembles the hard left of the 1970s: He embraces big spending by government, higher taxes to pay for it, the nationalization of more companies and an anti-Europe, antimilitary, foreign policy. In short, Corbyn rejects the "New Labour."