A recap of the story so far.
Deputy PM Nick Clegg was "obsessed" by the Treasury's distributional chart, confident it provided irrefutable proof that George Osborne had produced a "progessive" austerity budget.
Then the IFS refuted it, authoritatively, showing that the new measures were regressive, not progressive. "Budget will hit the poor harder than the rich" was not the front-page headline Clegg wanted to read in Britain's leading LibDem supporting broadsheet.
That's not fair, said Nick, on the Today programme this morning.
Sure, he prayed in aid Labour's policies. The new regressive decisions taken by the Coalition are better balanced when combined with tax reforms inherited from the previous government.
But Clegg's main point was much more brilliant than that. PoliticsHome reports the main reason he was able - with a perfectly straight face - to "reject" the IFS analysis of the budget.
Deputy prime minister Nick Clegg has rejected a budget analysis from the Institute for Fiscal Studies which said that the budget would impact the poor more than the rich. Clegg claimed that the IFS didn't include in their analysis possible future changes which the government may bring in.
Here's the quote:
Mr Clegg complained that the IFS analysis did not take into account what the government may do in future budgets, saying the budget could only be found to be regressive "if you exclude other measures, which we are including, and if you disregard what we're going to do in future budgets."
The IFS said the budget appeared more progressive when some Labour measures were included in the analysis.
He added: "Nothing has included, of course, future changes which we will make, which we will show, as we have done in this budget, that we're going to take very exceptional measures to ensure that fairness is instilled."
I've gone back and checked the claim.
And Clegg is right.
The IFS has entirely left out from its analysis of the government's budget all possible future measures which the government has not yet announced, even though some of these might turn out to be fairer than anything you might hope to see.
Let's quickly pass over a small logical wrinkle in the argument which claims that the proof that these future measures will be intended to be really, really fair - and so won't fail the progressive/regressive test next time - is just how fair the (regressive) budget measures were intended to be before they failed it this time.
The central point is that Nick Clegg's intentions are undoubtedly good. Is it not then reasonable to ask the pointy-heads to reflect the new spirit in the land? Can anybody seriously defend the IFS' old politics insistence on offering exactly the same statistical analysis as they would if these changes had been made by a nasty Clegg-less Tory government rather than this bold and even cuddly Cameron-Clegg progressive alliance?
So that leaves only one small methodological issue to sort out. To be fair to the IFS, Nick Clegg has yet to explain precisely how you might statistically model this "progressive premium", based on his heartfelt aspiration to be very fair in future, in budget analysis. Perhaps Danny Alexander may be able to suggest a workable formula.
To enter into the spirit of Clegg-Cameronism, my proposal would be to try to model and incorporate a "progressive boost" to the distributional charts as an "effort prize" to reflect the Coalition's good intentions. For example, if the bottom decile were to gain a nominal £1 a week on average incomes, every time that the Prime Minister or his Deputy use the "progressive" word, they might quickly make rapid inroads into the gini coefficient by the time of their party conferences this Autumn. That might at least do something to mitigate the impact of George Osborne's welfare cuts in increasing inequality.
So there is work to do there. I am sure that the IFS will get their top technical team onto this challenge pronto.
But I suspect that the really good news is that the next budget might just have to meet the Coalition's own "fairness test" properly - and for more than 24 hours next time.