In the past few minutes, Tom Watson has announced that he is stepping down at this election. In a surprise letter, the Labour deputy leader says his decision is 'personal, not political' and that he is 'not leaving politics altogether'. In the meantime, he wants to spend more time campaigning on public health.
There are some curious lines in this letter, and Jeremy Corbyn's response. The Labour leader picks up Watson's comment about not leaving politics, and writes:
'I am proud and glad to have worked with you over these four years and I know this is not the end of our work together.'
Given the warmth of the two letters, despite the fact that Corbyn and Watson had been at loggerheads and barely speaking for more than a year, it's reasonable to conclude that there is going to be another chapter in Westminster for Watson.
But this will be a blow to Labour opponents of Jeremy Corbyn, who had come to see Watson as a key reason for staying and fighting in the Labour party, rather than abandoning it. A number of MPs who had held talks about quitting had stayed either because Watson himself had persuaded them to, or because of an operation led by the deputy leader to keep the party together.
He had planned to launch a network of 'moderate' MPs, activists and councillors who could work as an alternative power base to the increasingly dominant left. Part of his plan had been to get the Labour party to the point where Jeremy Corbyn's leadership was so unstable that his own allies concluded that it was time to replace him. On this measure, Watson's work may yet be proven a success: much of the focus in the Labour party is on who takes over from Corbyn, rather than on supporting him blindly as his allies once did.
But this all presumes that Labour will not be successful in the general election. And the one sure thing about this election is that all confident presumptions aren't based on much. Besides, the success of Watson's stay-and-fight strategy will see MPs who find Corbyn's positions on many issues deeply repugnant still campaigning to get him into No. 10. Their failure to remove him as leader may mean that they end up with him as Prime Minister when privately they had expected and hoped that they wouldn't have to go into an election making such a bid at all.