Cameron's self-acquittal from the charge of telling his backbenchers something false was simply being "quite sure in my own mind" that the falsehood was true at the time. Clegg acquitted himself of directly misleading Cameron, while tacitly acknowledging that indirectly misleading the Tories on this point was a deliberate LibDem negotiating strategy.
Clearly, all's fair in love, war and coalition negotiations. So it must be acknowledged that the LibDems played a blinder in the poker game of bluff and counter-bluff. Much credit for the 'psy ops' choreography of the sense of hope and despair among rival bidders with their dramatic switches from Tory to Labour and back again must surely go to Captain Ashdown of the secret service. But this was never just, nor even mainly, about bartering up the price. As Ashdown made clear, trying and failing with Labour was absolutely indispensable to constructing a narrative which could deliver a united LibDem party for a Tory deal. (Ashdown's Today programme intervention on the Monday morning was a masterclass in the political dark arts, laying a false trail in the interests of party unity).
For all of the efforts of Andrew Adonis and Alastair Campbell, Labour had something of a shocker. Peter Mandelson made several wry observations as a shrewd political onlooker. As the second most powerful figure in the government, he must surely share with Gordon Brown the responsibility for the apparent absence of serious Labour preparation for a Hung Parliament. Ed Balls claimed he didn't even know who would be in the room on the Labour side for the first meeting: was a government ever to result from what Sam in the West Wing might have called a "pick-up meeting"? (It was hardly difficult to work out what offer to make for the LibDems: I sketched the contours publicly back in January 2009 for the New Statesman). Was the lack of any serious preparation for what was always Labour's best hope from the election the clearest sign yet of excessive Labour defeatism in the final six months?
Mandelson's final insight - that partnership, alliance and coalition may be the future of British, and hence Labour politics - is correct. The events of May 2010, even of the outcome was unlikely to be different, demonstrate several ways in which Labour's ethos, culture and structures are ill-equipped for this. And the outcome of a Tory-LibDem coalition may present significant psychological barriers to serious attempts to change this.
The Celebrity Masterchef-style of the documentary's voiceover focus on the principals meant the documentary underplayed the real politics of what made the Coalition possible. Robinson stressed how much the Clegg-Cameron personal chemistry mattered. This did underpin the LibDem leader's belief that the electoral arithmetic made a deal with the Tories much the better outcome. But that happy chemistry could be decisive only if the leader could persuade other LibDems more sceptical about the Cameron charm offensive - his shadow Cabinet, MPs and Federal Executive during those five days, and the broader party at the special conference after the deal was struck - that this was the right deal for the LibDems.
Clegg's impressive political achievement in May was to keep his party united while making his centre-right alliance. It may still matter, perhaps in the Autumn of 2011 or the Spring of 2012, that the LibDem leader placed enormous emphasis on persuasion and party management - mandated to do so by his party's democratic culture and structures - while Cameron's more perfunctory efforts have left a significant legacy of mistrust. It was not just that Clegg ensured all hands were dipped in the blood. Many LibDems signed up for the Coalition with a song in their heart, or at least with considerably less anxiety than seemed probable.
Yet what could also be seen in Robinson's documentary were the contours of several clear fault-lines which could one day divide Clegg from his still united and pro-Coalition party.
Firstly, it was brave for Clegg to own up to his other deception: making a pitch to the electorate on the central issue of the election which he did not any longer believe. It seems an unnecessary risk for Clegg to make up and energetically promote a story about the Governor of the Bank of England's powers of persuasion - an account which Mervyn King says he does not recognise - and then to find a prime-time moment to say it was never true, just ten weeks later.
But there is no mystery about why Clegg stayed stum. Whatever he and David Laws had concluded about the deficit, he would not have carried his party, nor kept his Shadow Chancellor and primary electoral asset, had he announced a conversion to Osbornomics in March or April rather than June.
His LibDem colleagues have signed up to the Budget but for Clegg, this is now a matter of conviction too. As Steve Richards wrote after the Budget,
Senior Liberal Democrats speak to me of the party's "deferred anger" over the coalition's extreme approach to public spending cuts. They suggest anger is delayed until the referendum. But those who assume that Clegg will walk out afterwards misunderstand his view of the coalition and its economic policies. Clegg is in a similar position in relation to his party as Tony Blair was over Iraq. Blair used to go around telling his colleagues: "It's worse than you think. I believe in the policy." Clegg is known to have told friends after George Osborne's Budget: "The good news is I'm not a patsy. The bad news is I believe in the Budget."
If Clegg's a believer - perhaps to a Monkees soundtrack ... he couldn't leave her if he tried ... - this is a contested, and probably a minority, LibDem view. That Vince Cable was influential in recommending the Coalition as a "head over heart" choice to MPs is not news. But he was candid in admitting he gave serious consideration as to whether to personally play a role in it. Cable will defend the Coalition and the Budget too, but as the grown-up political compromise as coalition give and take, without having to claim a Damascene conversion when the Tories prevail.
Secondly, it was quite clear that Clegg had never bought into the "head versus heart" line of the natural Lib-Lab alliance anyway. Labour had many good links to Paddy, Ming, Charlie, Vince and Danny Alexander - but had to go through more formal channels to the LibDem leader himself. That is partly ideological, for the Clegg-Laws group which is instinctively economically and socially liberal. And perhaps there is also a generational shift here. Ming Campbell's sceptical detachment about the Cameron-Clegg alignment - "they are not quite two peas in a pod but they are very similar" - reflected the primarily anti-Tory commitments shared by Cable and represented in the wider party by Charles Kennedy, which are not shared by a more equidistant generation of LibDems. (And this may particularly be true of a later generation whose formative political experiences come after 1997, shaped by their response not to Thatcher but to Blair, at whom the "Labservative" campaign strategy was pitched).
It is enormously premature to claim that May 2010 realigned British politics permanently, but it would be mistaken to anticipate any easy return to Lib-Labbery being the "default" option in future. Labour pluralists like John Denham note that the Coalition's agenda means future cooperation would require significant LibDem changes; equally, social liberals are right to suggest it would take a rather different Labour party too.
Thirdly, rather more immediately, there is a bubbling under but fundamental tension about what this Coalition is for. Clegg and Cameron prefer to present it to the public as a genuinely shared undertaking, in which they have found a common philosophy to the questions of the age. This allows both to present themselves as conviction politicians, not eternal hagglers in the Coalition bazaar.
The price paid for that is an existential danger to Nick Clegg's party. If there really is a common Liberal Conservative project, why is there any need for two separate parties to carry it out? (Clegg might also be tempted by a pragmatic "save our seats" case for Coalition electoral alliances too - which would be the way to sell it to the LibDem backbenchers - but the wider party will be aware that this involves the public presentation, including by the Tories, of an alliance of conviction).
So if the LibDems remain mostly united behind the Coalition, they also mean different things by it. The mainstream of party opinion remains in favour of the Coalition as the contingent best choice in May 2010, and as having delivered compromises worth making since, not as the happy discovery of a new permanent political realignment. Cable may represent the LibDem centre of gravity on both economics and politics. By stepping out of the deputy leadership to allow Simon Hughes a platform, he ensured the tension would remain visible, without requiring constant Cable-led Cabinet level rebellion to prevent the party being entirely submerged.
Captain Ashdown, putting party unity first, will need to keep a foot in all camps. If Coalition were to be the future of British politics, those black arts will be needed again another day. Perhaps in a different cause.