In his statement on Margaret Thatcher's death earlier this week, Ed Miliband pointedly noted that "she moved the centre ground". The Labour leader is aiming to achieve a similar feat. Indeed, he belives the centre has already moved to the left since the financial crisis, creating the space for a more unambiguously social democratic approach. It is a notion that Tony Blair fundamentally rejects. In his most significant intervention in domestic politics since leaving office, the former prime minister writes  in the centenary edition of the New Statesman: "The paradox of the financial crisis is that, despite being widely held to have been caused by under-regulated markets, it has not brought a decisive shift to the left. But what might happen is that the left believes such a shift has occurred and behaves accordingly."
Following last week's fractious debate on welfare, Blair says that Labour must be "the seekers after answers, not the repository for people's anger". He writes: "In the first case, we have to be dispassionate even when the issues arouse great passion. In the second case, we are simple fellow-travellers in sympathy; we are not leaders. And in these times, above all people want leadership".
Rather than retreating to its ideological "comfort zone", Blair argues that Labour must remain on "a centre ground that is ultimately both more satisfying and more productive for party and country". In a signal of his disapproval at some of Miliband's recent pronouncements, he writes that Labour must not "tack right on immigration and Europe, and tack left on tax and spending". Miliband has argued that the last Labour government was wrong not to impose transitional controls on migration from eastern Europe and has called for the introduction of a "mansion tax" on properties worth more than £2m.
Blair writes: "The ease with which it [Labour] can settle back into its old territory of defending the status quo, allying itself, even anchoring itself, to the interests that will passionately and often justly oppose what the government is doing, is so apparently rewarding, that the exercise of political will lies not in going there, but in resisting the temptation to go there."
Unlike some associated with New Labour, Blair argues that the party has been right to reject Conservative claims that it "created" the crisis by overspending. He points out that the current structural deficit was under 1 per cent of GDP in 2007-08 and that that public debt was significantly below 1997 levels at the time of the crash. "Over the whole 13 years, the debt-to-GDP ratio was better than the Conservative record from 1979-97." But he warns that now the crash has occurred "no one can get permission to govern unless they deal with its reality".
Blair goes on to pose seven questions that he says are examples of those Labour must answer if it is to address the need for "fundamental reform of the post-war state". In a sign of how he would have approached last week's debate on welfare differently, he says that the party should look at the "right balance between universal and means-tested help for pensioners" and ask what is "driving the rise in housing benefit spending". He adds: "If it is the absence of housing, how do we build more?" Blair also urges the party to explore how it can focus on "the really hard core of socially excluded families, separating them from those who are just temporarily down on their luck". In 2011, the coalition launched a scheme led by Louise Casey, the former head of Blair's Respect Task Force, aimed at helping England's "120,000 most troubled families".
On public services, Blair says that Labour should ask how it can take "the health and education reforms of the last Labour government to a new level, given the huge improvement in results they brought". Blair has recently praised  Michael Gove's free schools as "a great idea" and has accused the teaching unions of obstructing "necessary educational change". In addition, he calls for Labour to explore how "developments around DNA" can help reduce crime and how technology can "cut costs and drive change in our education, health, crime and immigration systems".
Hinting at his frustration at the party's perceived lack of policy development, Blair writes: "There is no need to provide every bit of detail. People don't expect it. But they want to know where we're coming from because that is a clue as to where we would go, if elected." The danger for Labour, he adds, is of "tactical victories that lead to strategic defeats".
Miliband, who has consistently spoken of the need to move on from New Labour, is likely to be unfazed by Blair's intervention but the former Prime Minister's words will reinforce the concern among some in the party that Labour risks being defined as a party of opposition, rather than a government-in-waiting, as it continues its crusade against austerity.