The precipitating factor behind the latest round of chuntering was the aforementioned Article 50 vote and the deep splits that cleaved into the Parliamentary Labour Party. As it happens, I believe Jeremy Corbyn absolutely made the right choice, and I'm sure any leader would have done the same in his position. Plebiscites and referenda are regressive and a step back from representative democracy, let alone the more substantive forms of democracy we should be aiming for. Nevertheless, we have to deal with the outcome of Dave's gamble because we - the parties, the campaigns, the voters - all signed up to it, and woe betide the political consequences for any of the big parties should they seek to defy the result.
The problem is, from the standpoint of Corbynism and its watchers, is while the enthusiastic uprising of hundreds of thousands of new members put their man in the leader's office, they themselves were overwhelmingly pro-EU while Jez was, by repute, historically opposed. And since the referendum there has been a strand, in and outside the party, that has tried tying the responsibility for Remain's loss to him. Never mind that the Prime Minister of the day only persuaded fewer than half of his party's voters to support his case. Nevertheless, this notion that Jez was/is a secret Brexiteer has persisted and that his actions during the last fortnight should be read in these terms. Pure poppycock, but it has certainly knocked the stuffing out of sections of his support. Is this the beginning of the end?
Firstly, no. There is not going to be a leadership challenge. There is no appetite in the party, and the PLP remain mindful about what happened last year. As the boundary review and battle over merged seats lies ahead, no one is in the mood to upset the party membership. I don't think shock losses in in Copeland and sunny Stoke-on-Trent Central make that any more likely, either. Nor is anything going to come from the unions. They are very concerned about the poor polling figures, but cannot be seen and will not make the first move to oust Corbyn, especially as it would sow serious division between them. Two years hence the situation might be different, but not now.
All that said, how long can Corbynism go on for if it's feeling the pinch of real division and failing to gain traction in the country at large? The answer to whether the moment is over is ... not yet. Labour is in a dark place, but we should be wary of treating politics as if everything is fixed and ordered in advance. Look out the window and everything is all over the place. In Britain, the dynamic that fed UKIP is dissipating and the LibDems are making an unlikely comeback. Brexit so far has kept the Tories together, but as negotiations get underway it will surely be impossible to keep a lid on things. And with the danger of talks collapsing completely which, thanks to May's complacency and the arrogance of her lieutenants, cannot be completely ruled out the possibility is the roughest, most frightening part of the road to travel may still lie ahead. And then there is the small matter of Donald Trump's innumerable idiocies and the government's evident desire to act as his bag carriers. To go all Rumsfeldian for a moment, these are the known unknowns. Even without them, British politics is still wracked by uncertainty. These problems, insecurity, precarity, fatalism, frustrated aspiration, have not gone away and the government is set to do little about them. These will find expression in some way - indeed, Corbynism is a symptom of it. The spectre of the unknown unknown is abroad.
Is the Corbyn moment over? If we understand it as a consequence of the flux and pulse of political crisis, probably not. It might in fact just be starting.