The message of this book chimes uncannily with the audacious speech by Ed Miliband to the Labour conference in September. The Verdict analyses Labour's enormous achievements in government, as well as how and why we fell short. Its lessons for the next time the party takes power are clear, and members of Miliband's new shadow cabinet would do well to read it.
However, even journalists as scrupulous as Polly Toynbee and David Walker underestimate the constraints of power, because they are observers rather than participants. They underestimate, too, the obstacles to a Labour government's successes being reported by the hostile, right-wing-dominated media.
They also get some things plain wrong. For example, as a former minister for Europe, I was baffled by this throwaway line: "On Europe Labour barely bothered, during years when leadership in Brussels and the national capitals was in short supply." On the contrary, and despite the visceral anti-Europeanism of the media and our political culture, Tony Blair put Britain for the first time at the centre of Europe. His advocacy of a full-time president and foreign representative to speak for governments through the European Council was exactly the reform needed to supply the strong leadership that Europe craved.
Yet the book is a good place to start learning from the past as Labour regroups and rebuilds in order to win again in the future. Toynbee and Walker cite the former No 10 policy director Geoff Mulgan, who said that governments underestimate what they can do in the long run and overestimate what they can do in the short run. I recall only too well Downing Street "initiativitis", which made governing a task that involved worrying more about dominating the news agenda than about delivery. Criminal policy is a good example: no sooner was one crime bill introduced than another was coming down the pipeline, with implementation of the earlier one an afterthought.
I detect the same rush into legislation and incessant "initiatives" under Cameron and Clegg - the poorly thought-out cuts to child benefit are a good example of the consequences of making policy on the hoof. The government achieved its objective of generating a big story ahead of the Tory conference and showing "toughness", but the policy fell apart under scrutiny.
Toynbee and Walker allow, though rather grudgingly, that Labour did "nudge the political centre of gravity leftwards . . . on public services, on income distribution and even on poverty", but not sufficiently to prevent the Tories, with the Liberal Democrats dutifully in tow, from using the excuse of the global financial crisis to cut and destroy a great deal of what we achieved. However, they also argue - persuasively, it must be said - that Labour was so much in thrall to the zeitgeist of unstoppable market forces that this choked off the immense possibilities of fundamental change offered by three successive elections with clear majorities in an era when the Tory press had no proper alternative to back.
Blair was, in many ways, an amazingly accomplished leader, and had an eerie sixth sense for the Tory underbelly. But he and those closest to him never had to confront the Tories when they were on the up, rather than disappearing down the plughole. The Conservatives feared us, but so did natural Labour supporters. Although Labour's natural support base is notoriously and frustratingly fickle when the party is in power, the blunt truth is that, of the five million votes lost in government between 1997 and 2010, four million were gone by 2005. Simply repeating now-hoary New Labour mantras and avoiding the tough questions posed by Toynbee and Walker will not help us win back those lost millions.
So what does all this mean for Ed Miliband's leadership? I am sure that he is persuaded by Toynbee and Walker's case for a bolder Labour agenda, which, they insist, is eminently electable. They maintain that the results of May 2010 show there is a "progressive" core of voters, comprising 49 per cent of the electorate. This assumes splitting and reallocating the Lib Dem vote, and adding to it Green and Nationalist support. "What the voting demonstrated was potential for progressive policy, even at Labour's lowest ebb," they write.
Toynbee and Walker cite in support of this thesis the American pollster Stan Greenberg, who has shown that British voters strongly favour more not less financial regulation, more government rather than more free markets, and modest tax rises instead of savage cuts in public investment. That means a British electorate more in tune with Labour's fundamental values than those of any rival party, provided - and this is a big proviso - that the party can win the people's trust. As the authors put it:
Cameron's failure to break through with a clear majority was proof that Labour's statism was nearer to what the public wanted. The Blairites were wrong to assume the majority were individualist, aspirational and immune from worries about security or equity.
So, the party must move beyond New Labour, retaining the best of it but jettisoning the worst. We should neither go back to the anti-business stance of Old Labour nor accept New Labour's deferential stance on markets, obscene bonuses and commercial greed.
Although there must be absolutely no retreat from Blair's appeal to "Middle Britain", there must also be an acceptance that this was too often made at the cost of ignoring white working-class concerns, especially over affordable housing. About this, Toynbee and Walker are scathing: it was, they argue, "one of Labour's weakest links". Failings over housing and job insecurity were the real reasons why immigration became the issue that dared not speak its name for Labour, leading to a haemorrhaging of working-class votes. Similarly, although the party must continue to be tough on crime and law enforcement, we should recognise that in government we frequently displayed a carefree attitude to individual liberty.
Labour under Ed Miliband is capable of striking fear into the coalition because he understands the need to mobilise the civil society constituency which used, in the past, to be such an important part of Labour's progressive periphery, but which became more alienated from us the longer we stayed in government. This spans faith groups and trade unionists, greens and community organisations, human rights and third world lobbies, anti-racists and feminists, united in a commitment to fairness and justice. They are crucial to revitalising Labour's historic mission.
Miliband has argued that, to win back the millions of votes we lost while in power, Labour must develop an agenda that is radical, empowering, internationalist and green, one underpinned by a renewed confidence in the values of social justice, equality, freedom and democracy. That agenda promises a Labour government capable of surpassing the verdict passed by Toynbee and Walker on the Blair/ Brown era: six out of ten.
The Verdict: Did Labour Change Britain?
Polly Toynbee and David Walker
Granta Books, 367pp, £18.99
Peter Hain is shadow secretary of state for Wales. His new biography of Nelson Mandela is published by Spruce (£12.99)