So Ed Miliband has dramatically overtaken his brother as the favourite to be elected Labour leader with just hours to go. It's unclear whether the rumours fuelling this shift are based on an actual leak from the now-completed count, rather than on the general mood in each camp and on back-of-the-envelope calculations. But if the punters are right, this could be one of the most hopeful days in politics for a long time, as the conceited belief of New Labour's architects that what they had fashioned was irreversible turns out to be - at least to some extent - deluded. If, on the other hand, David Miliband prevails after all, a golden opportunity to construct some kind of meaningful alternative to Blair-Cam-Clegg-ism will have been lost, and for the foreseeable future the three London parties will continue to squabble (or, in the case of the coalition partners, swoon) over the same absurdly small piece of centre-right political turf.
Either way, then, this is a day that really matters. The Labour leadership is an elective dictatorship, and - whichever Miliband is elected - a fortysomething leader could well mean that this is the rank-and-file's one and only chance to genuinely influence the party's ideological trajectory for anything between ten and fifteen years. This is, in a sense, the UK's equivalent of the culmination of the Obama v Clinton battle in the Democratic primaries, with the winner having at least a 50% chance of becoming Prime Minister at some point in the future. Odd, then, that the country is scarcely on tenterhooks, and that in all likelihood a large percentage of the population isn't even aware that the result is about to be announced. But that's the price we pay for what has become the convention of holding party leadership ballots immediately after general elections, when public exhaustion with politics is at its peak.
UPDATE (1.40pm) : If the BBC and Sky are to be believed, it now seems pretty clear that the move in the money to the younger Miliband wasn't triggered by a specific leak from the count, as not even the interim leader Harriet Harman knows the result yet. That contradicts the earlier suggestions that she was to have been told last night, which would have been consistent with a leak. Pity.