One Scottish machine politician down; one more to go. Although to describe Michael Martin as a machine politician may be to flatter him. He was really the beneficiary of machine politics, put into the job of Speaker nine years ago by Labour operators calculating factional advantage.
The parallels between the fates of Michael Martin and Gordon Brown are screamingly obvious, but there is no necessary connection. The boxing analogy applies to both: the Prime Minister increasingly looks, as the Speaker did on Monday, as if he has taken too many punches and is not quite sure where he is. And they are both damaged by the popular rage against MPs' expenses, because they both tried to prevent the disinfectant of sunlight – another of David Cameron's effective phrases borrowed from America – from reaching the dark corners; they both acted too late to try to reform the system.
This week we saw the Prime Minister on television saying that "what we have seen" of MPs' expenses "has angered and appalled me". Which was a bit rich, because it was with his knowledge and tacit approval that the House of Commons Commission spent thousands of pounds of taxpayers' money fighting a court case to prevent their publication.
In the campaign of obstruction, the Prime Minister and the Speaker were like Sinn Fein and the IRA, pretending to be separate organisations but tied by deniable understandings. Harriet Harman, Brown's deputy, and the Speaker himself are the two most important members of the House of Commons Commission. In that sense, Martin is not so much a scapegoat as a sacrifice, left out on the hillside for the ravening furies of the gods of democracy. Although it would be too much of a conspiracy to suggest that Brown left him there deliberately in the hope that his metaphorical blood would appease the public's anger.
It is not an edifying sight. Much of the anger at expenses is unreasonable and unreasoning, making no distinction between the fair costs of maintaining a second home and claims that were not even "within the rules", such as for mortgages that had been paid off. But politics is not about what's fair. It is, often, about leadership. Nick Clegg and David Cameron have shown it; Michael Martin and Gordon Brown haven't.
It doesn't matter that Clegg paid back £80 for telephone calls to abroad, or that Cameron now thinks he shouldn't have claimed for removing his wisteria. Or that they have sprung into action guiltily after being caught out. Martin and Brown's first response to being found was to pretend that nothing had happened. Although it should be pointed out that, in Brown's abortive, tardy and much mocked YouTube proposals, he nearly got the reforms right: a flat-rate allowance for MPs representing out-of-London seats. His mistake was to tie it to attendance at the House, so that it looked like paying MPs to turn up to work.
So, yes, the Speaker's departure removes one of the moats around Castle Brown that could have soaked up the flood of public invective. Martin's going does not, however, resolve any of the tricky questions of mechanism or timing in getting rid of a prime minister.
It ought to follow from Brown's failure of leadership on the expenses issue that the case for his departure is strengthened. And so it is. It ought to follow from Alan Johnson, the Health Secretary, emerging from the abattoir of expenses with clean hands that the case for his taking over is strengthened. And so it is. But neither of those arguments is the same as strengthening the forces likely to make it happen.
The key to a coup is political will, and one of the big effects of the expenses furore has been to demoralise Labour MPs, from the furthest-flung of back benches to the front seats in the Cabinet. The other thing is that the gale force of voter fury makes it seem pointless for Labour to change leader. The idea that the Government could rescue itself simply by rearranging personnel looks beside the point. A ComRes poll for The Independent on Sunday at the weekend found few takers for the proposition that Johnson would make a better prime minister than Brown. Johnson has been dragged back by the "they're all as bad as each other" factor, hitting the governing party hardest.
So I am uncertain about the likelihood of a move against Brown straight after the European election results being announced on 7 June, even if Labour does come fourth behind the Liberal Democrats and the UK Independence Party. And the timing is not yet right.
The coup would have to be delivered by several members of the Cabinet, acting together and knowing that they have the support of a majority of Labour MPs. If Brown is prevailed upon to stand down, the party's rules provide for the Cabinet to choose one of its number as prime minister and acting leader of the party until a leadership election is held.
It may be fashionable among some of my fellow Alan Johnson supporters to advocate another handover without a Labour Party vote. That does not seem like a good idea. I agree with one Labour MP who wants a change who told me that such a switch would be "cynical and horrible".
A leadership election – a comradely affair between Johnson (as prime minister), Jon Cruddas and Hazel Blears, possibly – could help refresh the party. It would, after all, cheer everyone up and give the media something to talk about other than how venal MPs are. What was fascinating about Johnson's answers when readers of this newspaper asked him questions on Monday was that he advocated proportional representation: it made him look pluralist, humble and reformist. I don't agree with strict proportionality, but I think it right to honour Labour's 1997 pledge to let the people decide.
But if Labour changed its leader again it would be neither wise nor right to resist the clamour for a general election soon afterwards. The candidates in a leadership election would have to pledge to go to the polls soon. If there is a coup this summer, then, the new prime minister would have to go to the country in the autumn. But I sense no appetite on Labour's part for bringing forward their next appointment with their constituents.
So it may be that Gordon Brown has to limp on, wounded, until the autumn. Labour's annual conference hardly bears thinking about. But that might be the time for change. Then, Alan Johnson could promise a general election in the spring, close enough to the expected date of May 2010 for it not to matter.
Is it worth it? Of course it is. Johnson as leader could make the difference between a wipe-out and holding the Conservatives to a small majority. The one lesson that Labour MPs ought to take from the expenses story is that, if you can see disaster coming right at you, take evasive action before it is too late.
John Rentoul is chief political commentator for The Independent on Sunday. His blog is at www.independent.co.uk/jrentoul