With his victory seemingly inevitable speculation is turning to what happens next for a Jeremy Corbyn-led Labour Party. The obvious comparison has been 1983, Michael Foot and the SDP split. A more prosaic outcome is more likely as Corbyn's mandate is slowly eroded and his supporters struggle with his transition from poacher to gamekeeper.
His most vocal media supporter Owen Jones has written a blog post on the challenges facing a Corbyn-led Labour Party. Jones sets out several steps the party must take if it is to succeed in the long-term and build on the surge in grassroots support. It includes 'message discipline', pragmatically prioritising policies (perhaps dropping cause célèbres such as rail nationalisation), reaching out to middle Britain and developing a rapid rebuttal communications plan.
All of these are eminently sensible things for a political party to do, as ably demonstrated by New Labour and the Conservatives. The challenge is that Corbyn has defined himself against the behaviour typical of political parties and their leaders, with this 'authenticity' being central to his appeal.
Herein lies the inherent challenge of his leadership being a success; Corbyn will need to lead his party without behaving like a party leader, or he will alienate his support. Without the popular grassroots movement that gives him legitimacy in a Parliamentary party that is largely opposed to him and likely to show little loyalty (reflecting his own history of rebellion), he cannot succeed.
Corbyn will need to take the journey from outsider to being part of the establishment (which the Leader of the Opposition must be). It is the same challenge that has recently split Syriza, with leader Alex Tsipras succumbing to the austerity agenda he has long rejected, in the face of overwhelming support for Euro membership. President Hollande followed a similar journey from opposing austerity to eventually accepting it.
A similar, but less significant disappointment permeates President Obama's leadership and his perceived failures, whether healthcare reform, stimulus packages or Guantanamo. All three have compromised or retreated in the face of global circumstances beyond their control, having promised to be a change candidate when on the outside.
The alternative is to adopt more traditional leadership strategies such as message discipline - 'Long Term Economic Plan' and 'don't give the keys back to those that crashed the car' et al - against which he has defined himself. This could alienate supporters, who have turned to him as a rejection of such politicking.
That route, and the process of compromise and the realigning of policy positions it entails, has already begun. What were considered more extreme positions on NATO and the EU have drifted to softer stances over the summer. I expect more examples if attempts are made to construct a broad church of support.
In order to hold the Labour Party together, Corbyn will have to reinvent himself, his platform and his operation, transforming from political outsider to Leader of the Opposition, without alienating those that put him there in the first place. The question is whether Corbyn's supporters are prepared to join him on the difficult journey of compromise that is inherent to all politics, or see their democratic experiment end in bitter failure.