It is, to simplify, that there is no third way between the Vision Splendid of traditional socialism and mere conservatism. Throughout the final two programmes, the implication was that in its long, dusty and painful hunt for votes, Labour had no alternative but to betray its best self.
Labour's wilderness was certainly not a silent place. It was peopled with garrulous prophets, repentant and otherwise. There was Tony Benn, the somewhat smug patriarch of righteousness, and his flock; Neil Kinnock, whose agonisingly honest self- criticisms suggested a man who had tasted bitter truths and risen above them; Denis Healey, who confessed that he really ought to have bothered to save the country from Thatcherism (but was, he implied, a little busy at the time); Roy Hattersley, who had made do rather well on his diet of locusts and honey.
All saw the wilderness as a place of struggle and betrayal rather than revelation or hope. There was little positive explanation by Labour modernisers of their project, other than the need to destroy old negatives. The possibility of a new left politics barely got a look-in. This was history, admittedly, not advocacy. But it was history with a sad ending.
The final programme, broadcast last night, closed with shots of John Smith's coffin and funeral (and for Smith read socialism). The last politician quoted was Peter Shore, lamenting: "If the Labour Party plays too safe for too long, it will really be denying its own heritage.'' And the narrator concludes of new Labour politicians: "They have never tasted the fruits of power and their political legacy will be a party which has rejected almost everything it stood for when, 16 years ago, it was cast into the wilderness.''
This was what Blair described in the Observer as "superficial and flawed ... intellectually lazy and wrong''. Was it?
At one level, the film-makers were clearly right. If one lists the policies Labour activists embraced in the late Seventies and early Eighties - unilateral nuclear disarmament, hostility to the European Community, further nationalisation, high marginal income-tax rates, enthusiastic support for all strikers - then most of it has indeed been rejected by "new Labour''.
We can go further. Socialism, in the sense of a programme of state action and ownership for egalitarian ends, aimed at dispossessing the capitalists and resolving the class struggle by parliamentary means, is about as relevant to Nineties politics as Muggletonianism. (Latter-day admirers of the prophesies of Ludowick Muggleton are hereby encouraged not to write in.)
Does this mean that, so far as electoral politics is concerned, "the left'' is dead, too - that we are all Conservatives now? Blair thinks not, and rightly. It is a historic oddity that we are still obliged to discuss politics by sole reference to the seating arrangements of the French National Assembly more than 200 years ago; but "left'' is still recognisable as a clutch of attitudes and values which distinguish some political humans from others.
Blair describes them as "solidarity, social justice, equality, community''. These values can mean different things at different times, but there are post-socialist ways of trying to live up to them. Let's take them in order.
"Solidarity'' was the watchword of trade unionists linking arms against employers; but if it really means standing together, that must surely include the un-unionised and people living on fixed pensions who were hurt by the militant unionism of the late Seventies. It presumably applies to victims of crime, too.
"Social justice'' implies that society is inherently unjust unless civilised by political action. Today, that suggests support for a decent welfare state and attacks on dangerous concentrations of wealth and power. But it could involve radical changes to pensions and welfare, so long as the condition of the poor is not made worse - which would be manifestly unjust.
"Equality'', if taken seriously, is unattainable in a free society. If taken unseriously, it merely means equality before the law. If taken semi- seriously, however, it means equality of opportunity; good schools for the poorest; the elimination of barriers to personal advancement; grants for higher education and so on.
And "community'' means - well, you've got me there. Labour in power has mostly been intensely centralist and unenthusiastic about local power. But this time round, it might mean devolution of power, the rebuilding of local democracy and support for those non-political institutions or "civil society'' which bind people together and offer haven from a world of struggling, competitive individuals and selfish consumers. And if it meant that, it would be a good thing.
Blair's four values, in other words, could indeed influence a new Labour government. Whether they will is unknowable because we are talking about a possible future Britain, a country in which power was devolved to revitalised local authorities, academic excellence was demanded for all state schools, Scottish and Welsh parliaments established, a minimum wage enacted, the tax system changed, the Lords and Commons reformed, monopolies challenged, and so on.
There is a potential programme there which, if it were actually achieved in office, would represent "left'' values just as adequately, and perhaps more so, than the statist socialism nostalgically celebrated by Blair's critics. The changes to which he is committed would make any real Conservative choke.
Bryan Gould was seen last night saying that his old party had undergone "a painful withdrawal from hope and ideals". It seems to me that the real withdrawal has been a withdrawal from fantasy and self-deception. Old Labour's language was grossly overblown compared to its real intentions. It talked about the martyred dead and the new Jerusalem, but it gave us the compromises and managerialism of the Seventies. It talked about itself as "a crusade''. But it was Harold Wilson who used that phrase, and what happened to his knights?
In short, they meant it less and less. Socialism became something spoken, not done; by the time Labour last held power, the world was on the brink of the market and technological revolution which buried its statist thinking. Much of The Wilderness Years was devoted to people not recognising the fact.
Blair, by contrast, not only recognises but accepts it. Labour no longer falsely promises to change the world. It believes Western societies are broadly moving along the right track. There is no talk of overthrowing anything, no hint of eco-doom or hostility to free trade, no end-of-century pessimism. The tone is perky. There are, no doubt, limits to this kind of politics. If something is radically wrong with the world, then new Labour doesn't have an answer.
But for the time being, most voters seem to agree with Blair's modest optimism, just as they disagreed with those mournful and angry folk who roared and bickered in the wilderness. Life back in the mainstream may be less romantic; but it is where the rest of us live.