Tom Watson speaks during the launch of the House of Commons Culture, Media and Sport Committee report on phone-hacking on 1 May 2012. Photograph: Getty Images.
The resignation of Tom Watson from the shadow cabinet substantially changes the complexion of the row over internal Labour party processes and selection battles. Ostensibly, the arguments and allegations in recent weeks had been about the influence of Unite - specifically its explicit strategy of placing hand-picked candidates in line for winnable parliamentary seats. This all came to light because of an egregiously clumsy attempt to stitch-up the selection in Falkirk.
As details of that episode have been pored over and the Labour leadership has tried to get a grip, a recurring theme in discussions has been the friendship between Unite general secretary Len McCluskey and Watson (now ex) Labour party deputy chair and head of campaigns. It was hardly a secret or a surprise that trade unions had a profound role influencing constituency selections. Frankly, without union money it is quite hard to fight any kind of Labour campaign - internal or external. But something a number of MPs and shadow ministers have been complaining about in private is the very specific role that Watson has had in anointing potential parliamentary candidates.
The chatter around the party - more specifically, but by no means exclusively the angst-ridden and disillusioned Blairish side of the party - has been that Watson runs around the country making sure 'his' people get chosen and consolidating an already formidable control over the part machine. This, as I noted in my column this week, is pretty much the same machine that agitated internally for Gordon Brown to replace Tony Blair in Downing Street and that helped enforce Brown's will once the coup had succeeded. By reputation - no doubt somewhat exaggerated - it is an apparatus of whispers, smears, briefings and 'punishment beatings'.
When Ed Miliband became leader he had a relatively small following in the parliamentary party and certainly nothing that could be called a machine. So he inherited the old Brown-era one. Miliband has stayed studiously aloof from the grindings and whirrings of internal party machination, but the grumbling about the old techniques being back in play was getting hard to ignore. I was told recently that representations had been made to the leader's office by MPs and shadow ministers to the effect that the culture of 'dark arts' was running out of control and that it was in danger of making Ed, with his preference for idealistic, moralising language, look like a hypocrite.
I suspect noises of this kind were getting louder as a result of the publicity around the Falkirk case. A potentially unkind spotlight was perhaps about to fall on the way Watson is alleged to have been carrying out his duties. His resignation pre-empts what could have been - and of course still could be - a round of old-fashioned red-on-red bloodletting.