Jeremy Corbyn's historic victory today on the first round of voting with nearly 60% of the vote has been anticipated for weeks and does not come as a surprise. But for political commentators it still has the capacity to shock. It is no longer a question of 'JesWeCan'. It is now 'JeezThey Did'.
For the victory of Corbyn represents a rejection of the electoral logic and strategic calculus that has driven Labour Party policy for the last 25 years. Back in the 1990s, Labour strategy was straightforward. The UK's First Past The Post (FPTP) electoral system piled up safe seats in Scotland, Wales and the North of England for Labour, and in the affluent South of England for the Conservatives. General Elections were won in the centre, where the two parties fought over the marginal seats that would propel them to victory. Now, with Scotland firmly in the SNP camp, and the party under pressure from all directions elsewhere, the way forward is not so clear. We still have FPTP but the clarity is gone.
What is clear is that Corbyn and his team will have their work cut out to reunite the party after a bruising contest and to forge a policy platform and style of politics that will not only command the support of his MPs (most of whom did not support him and many of whom think he will be a disaster) but also overcome the scepticism of the electorate. He and his team will have to do this whilst trying not to alienate the more idealistic of his supporters, who will be looking closely for the first signs of betrayal.
In terms of policy, Corbyn will inevitably have to compromise in the short term. The Labour left is committed to scrapping Trident, withdrawal from Nato and also from the European Union, whilst most MPs and voters do not support these positions. It is no surprise, therefore, that Corbyn has already stepped back from these proposals to some extent. Other policy commitments, such as bringing the railways back into public ownership, raising the top rate of income tax, and creating a national infrastructure bank to boost economic growth, are more popular with voters and I would expect these policies to move centre stage. Whatever the policies, however, Labour's opponents in parliament and the media will seek to portray the party as dangerously extreme and divided.
The question of division leads us to the next question: what style of politics will Corbyn and his team pursue? Three questions need to be answered. First, will Corbyn surround himself - as he has done throughout his career to date - with people who share his views or will he seek to construct a big tent and welcome talents from across the Labour family? The answer to this will have massive implications for party unity and for its future electability.
Second, and almost as important, how will Corbyn choose to approach the weekly Prime Minister's Questions? Will he immerse himself in the ritual and attempt to better David Cameron week-by-week or will he treat it with the contempt that many of his supporters think it deserves and concentrate on building his case in the country rather than playing the discredited old parliamentary games?
Finally, and most intriguingly, how will his new Deputy Tom Watson play his hand? Watson is a party insider insider and - many would argue - a bit of a political thug. He has the power to either make Corbyn's task harder than it needs to be or to bring the party machine behind him in the name of unity. And if, in a few years time, it is clear that Corbyn is leading Labour to disaster, I wonder what role Watson will play as Corbyn's opponents try to remember where they buried the political hatchets?