On Tuesday afternoon everything looked as though it were, at long last, going according to plan. Ken Livingstone, he was confident, would be on Labour's shortlist to be London's first mayor. Which was what Mr Dobson wanted and told the Prime Minister he wanted, not least because while polls showed he had a sporting chance of beating Livingstone in a Labour electoral college, they suggested he had almost none of beating him among the wider electorate if Mr Livingstone, bounced off the party shortlist, decided to run as an independent.
The clearest signals from Party HQ had indicated that this was indeed what the Prime Minister wanted. The networks had been alerted that Tony Blair was to declare his undying admiration for Mr Dobson's qualifications for the job, and his undying opposition to Ken Livingstone. Just as for Lord Lundy, in Hilaire Belloc's cautionary tale, the press was squared, the middle classes all prepared.
Then, by the evening, it had begun to unravel badly. Suddenly it looked as though Mr Livingstone would be dropped from the shortlist. Suddenly it seemed as though Mr Dobson had sacrificed his Cabinet post to the interests of his party and its leader only for it to appear that, unless there were a change of heart today by either the panel or Mr Livingstone, he was staring at a future no better than that of a Labour backbencher - the equivalent of the governorship of New South Wales to which the hapless Lundy was consigned in Belloc's poem.
This was bad enough. But several factors made it worse. First, the latest canvass returns showed Mr Dobson ahead among party members for the first time. Second, the row that had provoked the panel to reconsider its intention to keep Mr Livingstone on the list contained artificial elements. It was true that he'd considerably raised the stakes, possibly buoyed up by that morning's poll showing that he could easily win as an independent, by saying he would stand down as candidate if he disagreed with the (not yet written) manifesto. True, this was quite something, given that manifestos tend to be produced about four weeks before an election. Nevertheless, the only issue on which Mr Livingstone had continued to insist he differed from the Government was one over which the mayor would have no statutory power if and when he took office - namely the financial and ownership structure of the London Underground. What's more, his rival Glenda Jackson, had, when asked a similar question, apparently repliedthat she wouldn't sign up to policies she did not believe in. And got away with it.
Nor, Mr Dobson was entitled to reflect, was this insistence on absolute agreement to every item in a party manifesto quite the long-established tradition that it was argued to be. Rather famously, for example, Roy Hattersley and Denis Healey had made it publicly plain during the 1983 election campaign that they disagreed with the party on two fundamental issues - Europe, and unilateral disarmament. To complete the irony, Roy Hattersley, then the leading party revisionist, to whom much of the credit must go for preserving the fragile thread by which Labour was eventually restored to sanity, had spent much of the period fighting against Tony Benn's demand for MPs to sign up to a "loyalty oath" to abide by every detail of party policy.
All of which was history, of course. But it all helps to explain the strong hints yesterday from the Dobson camp that he could step down if Mr Livingstone were bounced off the shortlist today. He will, after all, be left in the worst possible position if Mr Livingstone is dropped and runs as an independent.
Which brings us to the darkest and most intriguing conspiracy theory of all: that this had been in the minds of the party princes when they engaged with Mr Livingstone on Tuesday. True, the argument might go, Mr Dobson is ahead in the party canvas returns. But Mr Dobson is running third in the latest poll of London electors - behind the rather overlooked Glenda Jackson. Ms Jackson has been playing matters rather skilfully in the last few days, moreover. She has shown she is her own woman. She criticised Mr Dobson's use of party lists. She refused to stand down and back him when the other candidates did so. She is making a hit on the talk shows, sparkling with Hollywood reminiscences. If Mr Dobson were provoked into departure, then wouldn't she be at least a plausible candidate?
For the real conspiracy junkies it is possible to go even further. Mr Livingstone's main opponent on the panel was Ian McCartney, a close ally of John Prescott, who is known to have more than a soft spot for Jackson's candidacy.
In fact, the conspiracy theory doesn't quite work. It serves to demonstrate that in the scarcely thinkable shambles of Mr Livingstone's being bounced off the list and Mr Dobson's resigning, a kind of plan B could still be salvaged - though at goodness knows how high a price to the party in London. But nothing like this was engineered on Tuesday. This is partly because Mr McCartney was clearly genuinely provoked by Mr Livingstone's high-handed treatment of the manifesto question. But it is also because to imagine it possible is to imagine a central intelligence on the issue of the mayoral campaign that has been signally lacking during the 18 months or so when the question should have been decisively sorted out.
There are lots of ifs, of course. If Frank Dobson had come out earlier, he could have shaken off the notion that he didn't want the job. If Mo Mowlam had been prepared to do it in July, she could probably have stormed Mr Livingstone out of the picture. But, most of all, if Mr Blair had shown any of the determination that he did on the infinitely more important issues of Kosovo and Northern Ireland, we would not be where we are now. The mystery is that someone who could be as decisive, heroically impatient even, on these huge events, spent most of the last year or so, when it came to the mayoralty, waiting for something to turn up.
Hopes now appear to rest with Mr Livingstone and whether he will fulfil last night's indications that he may after all be the one to back away from confrontation. There are possibilities of a compromise - such as putting the manifesto to a ballot of party members. Either way, it remains as sensible as it always was to take him on in a contest within the Labour Party. Glenda Jackson might be a more charismatic candidate, though, while I seem to be practically the only person in London who thinks so, Frank Dobson's solid if uninspiring competence as a minister strongly suggests he would make the better mayor. But Mr Livingstone will almost certainly not remain on the shortlist unless he does modify his stance, because the panellists have gone too far now. His declaration last night implies that he will do so.
The oddity is that the nature and composition of the contest was ever left in the hands of a man whom nobody in the Government wanted to exercise the slightest influence on the nation's political life.