I found out about Alan Johnson's resignation as Shadow Chancellor in unusual circumstances - standing a few yards away from Gordon Brown, as he began to sign books in the basement bar of the Old Vic Theatre, ahead of his lecture on 'a better globalisation', co-hosted by the Fabian Society with Southwark Council, in their series of John Harvard lectures, as implausible twitter rumour turned rapidly into hard political fact.
A little later on stage, Brown paid tribute to Alan Johnson's contribution to Labour politics, while expressing confidence in both Labour leader Ed Miliband and new Shadow Chancellor Ed Balls.
Yet it is their relationship with Gordon Brown which has excited much initial comment.
The applause for Brown's comments about Johnson reflect that many people's first instinctive reaction was sympathy for this widely liked politician. Nobody should seek to comment definitively on painful personal difficulties from the outside, even once rumours have been replaced by clearer facts. But the mystery may inevitably include a question mark over whether the personal pain could have been politically survivable had the appetite for politics remained. (Generally speaking, in 2010, issues such as extra-marital affairs are not politically fatal, as many examples from Robin Cook to Chris Huhne show; an alleged spouse's affair even more so, as Harold Macmillan might verify). The gruelling personal pressures of the frontline political treadmill are often underestimated, but the question may also remain as to whether this also looks somewhat like a resignation of choice.
Ed Miliband and the paradox of post-factionalism
This enforced change may well require a shift in the Ed Miliband leadership style.
As Labour leader, Ed Miliband has had to juggle with a paradox of post-factionalism.
His more pluralist 'new generation' pitch depends on an explicit repudiation of the factional battles which disfigured Labour's internal debates. Yet any post-factional strategy is surely complicated by everybody testing the promise by counting heads to gauge the level of fairness to the old tribes. AJ's departure may mark the end of this road.
Ed Miliband has a clearer sense of how his party needs to change than his critics acknowledge. But his style is instinctively collegiate - as a matter of inclination as well as the circumstances of his narrow victory in a divided electoral college. Once his brother David chose the backbenches, the choice of Alan Johnson as Shadow Chancellor was primarily a symbol of post-tribal ecumenicalism, which trumped economics. So party management seemed to trump economics - with Ed Balls kept away from the role he covered, while AJ was offered a cohabitation which bordered on co-leadership of the party's policy review in particular.
If this decision to choose AJ was widely praised, there were plenty of teething troubles in practice. Despite Johnson's feted communication skills, the AJ-Ed relationship got off to a rocky start, as captured in Mary Riddell's Fabian Review interview, as the Shadow Cancellor making several head-on challenges to the leader while rather over-doing the self-deprecation while struggling to master a novel economic brief. By the time Ed Miliband was confidently defending his Shadow Chancellor's gaffe over National Insurance rates, there had been a palpable shift in confidence and power between the two men.
Yet Johnson's surprise resignation means that Miliband now has the Shadow Chancellor he decided against, though one he may sometimes more instinctively agree with.
If Miliband's strategy was to defer to Alan Johnson, this time the emphasis may need to be somewhat more on demonstrating that his leadership sets the framework for his senior colleagues.
More broadly, perhaps this is the right moment to call time on "post-factionalism through factional balance" and for Ed Miliband to try operating a new and plural meritocracy of talent within the Parliamentary Party. After all, the boundaries have lost much of their meaning. The faction once known as the Brownites scattered in every direction during the leadership campaign - that micro-tribe supplying two different leadership candidates and the campaign manager of a third. If the Blairite crown can switch from David Blunkett and John Reid to David Miliband to Alan Johnson and now to persons unidentified, it is difficult to see what contentful meaning it retains.
Ed Balls' challenge of reinvention
For the new partnership to last four years rather than four months, Miliband may need his new Shadow Chancellor to complete a personal reinvention as a frontline politician.
Ed Balls was - from 1997 to 2004 - among the most powerful advisers in post-war British government. As chief economic advisor, Balls had a decisive influence on several of the most enduring economic decisions of the Labour governments - including the independence of the Bank of England, and the decision to stay out of the euro, as well as the broad macreconomic framework which brought Labour a long run of economic success, and the great crash of 2008. Before the age of 40, Balls had made more impact on British economic policy and the Treasury than many post-war Chancellors.
That experience contains a mixture of blessings and burdens for the new Shadow Chancellor. What has been less often recognised is that Balls has already had to undergo a series of significant transitions since then.
On becoming an MP in 2005, Balls had to adapt to the different skills required by a frontbench politician, particularly in the media and public speaking, to those of forging policy and using political power behind the scenes.
As power passed from Blair to Brown, and Balls took up a Cabinet post, he argued that the party could leave the "prism of Brown versus Blair" behind. It was a nice thought, but proved rather premature. And this factional history was surely one of the reasons why Ed Balls struggled to get a serious run in the 2010 leadership contest, even though he had (like many in Westminster) anticipated a David Miliband-Ed Balls leadership contest for several years.
Yet, perhaps in part because he was freed from the hope of victory, Balls managed to end the leadership contest stronger than he began it. That was partly because his challenge to the Coalition resonated with Labour members. (Though, strikingly, a politician often attacked, and occasionally praised, for tribalism began to win praise from political opponents too, being made Parliamentarian of the Year by the Spectator for his destruction of Michael Gove over the cancellation of Building Schools for the Future).
It was also because Balls visibly relaxed and emerged as his own man with his own platform, rather than being defined purely as a second brain for Gordon Brown. This was widely remarked by many of those who followed the Labour leadership contest closely, and widely missed by the majority who did not.
But this will be put to the test over the next few days, with the Conservatives and their press allies making a determined effort to define both Balls and Miliband purely in terms of being a Gordon Brown continuity project.
The Tory trap
Yet those Conservatives who are over-excited about Balls' appointment for this reason risk luring themselves further into the trap of preaching only to the converted.
If their core problem in May 2010 was that running against Gordon Brown was not enough, it seems rather curious to hope that it might be their salvation in 2015. Last May, three-quarters of the public wanted a change from Labour. Where the Conservarives failed was in making their own case. As Tory pollster Andrew Cooper has pointed out, the failure to resolve the strategy or message always sent the party scurrying back to a "relentlessly negative" anti-Brown argument.
In 2011, never mind 2015, banging on about Gordon Brown and the last government is going to seem to many people like a very poor substitute for a missing strategy for economic growth. It will resonate with some people. It will be popular on the Tory blogs, among signed-up commentators and on the Tory constituency rubber chicken circuit. It might appeal to the 30% of the electorate who are very happy with the government and its economic strategy. But, to everybody else, it risks looking ever more evasive with every month and year that passes, with Ministers repeating the mantra on Question Time and Any Questions ever more likely to be heckled.
Ed Balls' challenge as Shadow Chancellor will be to ensure that it is this government's economic record which comes primarily under scrutiny, and not only that of its predecessor.