Gordon Brown was a big beast in an era when there were big beasts in British politics rather than the minnows and charlatans we have today. He was interested in ideas and concepts, not the fripperies of politics. He was tested by terrible tragedies: the loss of an eye as a teenager and, when chancellor, of his baby daughter soon after she was born. And what he has done since leaving office in support of primary education around the world is enormously commendable.

I see no point in re-litigating the Blair-Brown wars when all progressives need to work together in the face of the serious threat that the country faces. Though it is mildly interesting to see how the various battles appeared from the other side, in the end there were only a handful of people involved and even they don’t care much nowadays.

The publication of Brown’s autobiography, My Life, Our Times (Bodley Head), is, however, an opportunity to stand back and assess his time in politics as a whole. The book is circumspect in what it tells us about his childhood or any of his inner thoughts, but unintentionally it reveals all the tragic flaws that prevented him from reaching his potential as a great political leader.

His diagnosis is that he was the wrong kind of politician for his age. He was not cut out for a “touchy-feely era” and was unable to make the most of Twitter and other social media platforms. He believes that, as prime minister, it was his failure to communicate his success to the public that led to defeat. From the evidence of his autobiography, it is clear that the problem was not Twitter but that while he had a high IQ, Gordon was almost entirely lacking in EQ – emotional intelligence – which is an essential component of political leadership. His account of his encounter with Gillian Duffy in the 2010 election illustrates perfectly his tin ear; for him, the fault lay with one of his aides, who had failed to turn off the microphone, rather than with him, for calling Duffy a “sort of bigoted woman”.

He attributes many of his difficulties to the right-wing press, particularly the Murdoch titles Every media slight is recalled in detail, from the MPs’ expenses scandal to Barack Obama’s gift of a pack of DVDs (which, he tells us, didn’t even work on British DVD players). Having such thin skin is fatal for a prime minister. The one exception from his complaints about the media is Paul Dacre, the editor of the Daily Mail. The friendship between the two men was one of the most curious in politics.

Reading the book suggests a different diagnosis for his failure, at least to me. First and most important was Gordon’s inability to take responsibility. This is the primary test of leadership. The book is a series of mea non culpas, in which someone else was always to blame. The loss of the 2010 general election, for example, was his predecessor’s fault: “Well before Tony Blair left office, public support was moving away from us.” He doesn’t even accept that the election was lost: “Perhaps I am alone in thinking that the most remarkable aspect of the general election result in 2010 was that only ten million people voted for Tory austerity, whereas 15 million voted for parties with policies to keep the economy growing.” Labour was out of power because of Nick Clegg, not because of Brown.

The most striking example is his attempt to distance himself from decisions about Iraq. “I ask myself over and over whether I could have made more of a difference before the fateful decisions,” he writes. But he didn’t want another battle with Tony and he let himself down by not asking harder questions. He should have barged his way into the discussions. But his get-out-of-jail-free card is a secret US document that he claims he has discovered. It shows that “key decision-makers in America were already aware that the evidence on the existence of WMDs was weak, even negligible… It is astonishing that none of us in the British government ever saw this American report.”

According to his description, this was an internal document commissioned by Donald Rumsfeld to identify gaps in US intelligence on Iraq, which was released in 2011. I have asked the key foreign policy and intelligence officials in the Bush administration and none of them has heard of the document. All deny that any such information was hidden from American or British leaders. A senior US intelligence official involved in vetting the case for Iraqi WMDs said, “It would be highly improbable that the department of defence would have intelligence that Iraq does NOT have WMD. How would they prove a negative?” The problem with Iraq is that we got it wrong. There aren’t undiscovered documents that exonerate us.

Perhaps this unwillingness to take responsibility is explained by a comment he made to a friend in 2004: “I’ve tried not to be too exposed.” Gordon deliberately tried to avoid being associated with difficult decisions in government. But I think the explanation goes deeper. Robin Cook told me that he put it down to the influence of Gordon’s father, a minister in the Church of Scotland. Gordon writes that his father “did not need to say anything when he disapproved of my bad behaviour; his frown told me everything”. In his desire not to earn that disapproval, he took to avoiding responsibility. Unlike George Washington, he would have said: “Father, I cannot tell a lie. Tony Blair chopped down the cherry tree.”

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Brown’s second flaw was his propensity to nurse a grudge indefinitely and let it eat away at him. While I was reading the book I had a series of disturbing nightmares. On the last night I sat bolt upright in bed with a vision that encapsulated the book: the howls of rage of a Minotaur trapped in a labyrinth of its own recriminations. This theme runs throughout the book – John Reid messed up Afghanistan, Alan Milburn was “disingenuous” and “vacuous” in his disagreement on health policy, Tony had “the biggest and best flat in No 10”.

The main problem appears to be the collapse of his relationship with Tony Blair. When they entered parliament in 1983, he told Tony that no great friendship among the senior ranks of politics had ever lasted. He wanted them to be different but he now thinks that Tony concluded that a breakdown was inevitable. Gordon’s gnawing disappointment and feeling of betrayal drips off every page of his book: he had helped Tony broaden his appeal in the party and Tony had always told him he was the senior partner, and the taking away of the leadership from him was “incredibly unfair”.

Gordon had his brother keep a diary so that he could record the promises that Tony made at the time. He doesn’t seem to have considered that whatever was said between them in 1994, the reason Tony was increasingly unwilling to hand over the leadership to him might have been his refusal to co-operate in government and his attempt to oppose every reform that Tony tried to introduce.

It is important for Gordon to demonstrate that the differences between them were over policy, and policies that are now unpopular such as tuition fees and the euro – but in reality, it was a clash of personalities. He identifies the breaking point as an argument over the euro in 2003 but it started long before because of his outrageous behaviour. Every page of my diaries from the period began: “You won’t believe what Gordon did today.”

Tony had been discussing moving him or even getting rid of him altogether years before. The breakdown of the relationship was a tragedy. They could have been the Lennon and McCartney of politics, as Gordon approvingly notes, but instead it was Yoko Ono and the break-up of the Beatles from the beginning. The surprising thing is how much the government was able to achieve despite the split at the heart of it.

The third flaw was indecisiveness. The best example of this is the on-again-off-again 2007 election. Gordon still denies that he ever thought of calling one: “I had never wanted an early election.” He claims that he did not read a note proposing the idea that his aide Spencer Livermore produced for him at the beginning of August 2007. He now writes that he did see the polling favouring the Tories, which he denied at the time. He thinks that his mistake was to allow his aides to speculate publicly about an election, though he gives the game away when referring with approval to the launch of the “Not flash, just Gordon” billboard campaign, a precursor of an election.

The real problem was that he could not make up his mind and dithered until the last minute about whether to go for an election and then denied to the public that he had ever thought of having one. In my view, he probably reached the right decision – Theresa May has found out the cost of calling an unnecessary election in a similar position – but his denial that he had ever considered the idea gave the public a glimpse into his soul from which he did not recover.

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The final and perhaps most surprising flaw was his lack of any programme as prime minister. Gordon had more time than any previous incumbent to prepare for office, to put together a team and to decide what he wanted to achieve. He kept telling Tony that he had a series of great ideas but he couldn’t tell him what they were in case he stole them. In the end, the emperor had no clothes. When he came to office, he had no ideas and there was apparently little he wanted to do.

Gordon’s explanation is that Tony made him wait too long and the public was tired of him by the time he got to No 10. It is true that there are de facto term limits for British prime minsters but that does not extend to chancellors becoming prime ministers. Perhaps the problem was that he never fought an election to become leader of the party or prime minister, just like May. Unless you have to run and prove yourself, you arrive in the top job undefined and unready.

Gordon did all he could on coming to office to distinguish himself from Tony in small things. He claims that he abolished the order in council, which allowed Alastair Campbell and me to issue instructions to civil servants, as a way of ending sofa government. But he seems to have missed that Robin Butler, who was the cabinet secretary until 1998, later made it clear that introducing the order in council in the first place was a mistake and made no difference to anything in the running of No 10. Gordon complains of the series of “events” that distracted him on first taking office, including floods, pestilence and developments in Northern Ireland. But a successful prime minister needs to have the ability to move the agenda forward, despite the crises.

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It is clear that Gordon should not be blamed for the 2007-08 economic crash. It was, after all, a global crisis caused by the US sub-prime market. It is also clear that he did good work in gathering world leaders at the 2009 G20 meeting in London and chivvying them into agreement. In the end, however, I think history will give more credit to the Federal Reserve’s Ben Bernanke, with his deep knowledge of the Great Depression, and Timothy Geithner, then the secretary of the US treasury, for saving the world economy, because the rescue had to be American, just as the cause of the crash had been American.

It could be argued that Gordon’s greatest failure was the succession. He was so determined to win the crown that he adopted a “King Herod strategy”, killing off at birth any potential rivals who might challenge him, from Alan Milburn to Charles Clarke. In particular, it was his determination to stop David Miliband succeeding him that led to the victory of Ed, which led in turn to the rise of Jeremy Corbyn.

Gordon uses the book to try to reinvent himself as a left-wing socialist, praising Corbyn’s approach. He claims that his whole career was a battle against neoliberalism and globalisation and that he was only held back from more radical measures by Tony Blair. He now demands that the bankers be put on trial (which I suppose he could have done at the time). That is not quite how I remember the proponent of the private finance initiative and “prudence” between 1997 and 2007. It has certainly been a long journey from champion of neo-endogenous growth theory to the enemy of neoliberalism.

Gordon describes the book rather portentously as “the second draft of history”. I think it will instead be the raw material of history, along with all the other memoirs and accounts of those times. My guess is that history will be kind to him about his time as chancellor and the many achievements of the government, from Bank of England independence to tax credits, but less kind about his time as prime minister and about how he got there.

Whatever his flaws, Gordon Brown was a towering political figure. Now the need is not for recriminations but for all progressives to put the past behind them, come together to fight Brexit and stop the collapse of the economy and, perhaps, even our political system. Let’s draw a line under the past once and for all.

Jonathan Powell was Tony Blair’s chief of staff from 1995 to 2007 and is the author of “The New Machiavelli: How to Wield Power in the Modern World” (Vintage)