In a cramped eyrie of an office on the top floor of Hatchards, the Piccadilly bookshop, Lord Mandelson is coming to terms with the demands of an author's publicity tour by signing more than 300 stacked copies of his book, rushed to the printers by HarperPress this week.
There are rumours of an advance of £500,000, not confirmed, roughly an eighth of the advance given to Tony Blair for his book, out in September. And Mandelson is eager to rebuild bridges with a party in danger of breaking off its late-flowering love affair with him. Many are furious at such a graphic account of the New Labour years.
He reveals he will in future fund a sort of academy to train a new generation of Labour communicators, strategists and organisers – a sort of Hogwarts for spin doctors.
Mandelson is also eager to rebut reports that Blair is livid with him for the exposé and for pre-empting his own publication. "I have spoken to Tony quite a few times over the past 10 days and he has made it absolutely clear to me every day that we have spoken that he is perfectly relaxed about the book, and today, far from being livid, as a source told the Times he was, Tony told me he was certainly not angry and people have no business speaking on his behalf."
I ask him who he thinks might have spoken for Blair. There is a long pause, before he says: "It is not helpful to conjecture." Asked if he thought it had been Alastair Campbell, he said: "I am not going to be drawn." Clearly the infighting has moved from the corridors of Westminster to the publishing houses of Bloomsbury.
He also feels hurt that the former Labour leader Neil Kinnock has criticised him, accusing him of becoming a caricature of himself: "Neil's comment is based on never having opened the book. It only became available today. I think people should read the book, rather than have views and words put into their mouths.
"If they read the book, and not the serialisation, they will see it is a rounded, balanced account of one of the great achieving Labour governments, but they will see in the book what you would expect from me, a measured account by someone who does not pull his punches."
But has he not betrayed confidences for personal gain ? "It's a memoir. I did not want a nondescript work that glossed over everything. I cannot tell a story about myself without telling a story about Tony and Gordon. We were so intertwined. You either don't tell that story at all or you tell it truthfully, warts and all; you cannot be half-pregnant in a situation like this.
"The days of anodyne memoirs where everything is hushed up and swept under the carpet for 30 years are long gone. You would not find a publisher and you would not find anyone to buy it, and if anyone was unlucky enough to buy it they would be asleep."
The book is in part an attempt to explain his complex relationship with Brown and why he did not move against him last year when it was clear he was unelectable. For he is quite clear in the interview that Labour would be probably be in power now if it had been possible for Brown to be replaced by a consensual alternative.
"If you really force me, I think probably it would make a 20 to 30 seat difference to the result. They would have gone to 280 and we would have gone up to 270. They probably would have been the largest party, but not by a decisive margin."
Asked why, then, he tolerated Brown's continuation in office he says: "I felt a sense of personal loyalty. I felt a real bond between us and I was not going to be shaken on that.
"But it was also my guess that if Gordon stepped down and people got behind David Miliband, Ed Balls would have entered the contest, and before you knew where you were there would have been an ugly fight, not just between two people perceived to represent new and old Labour, which was the last thing we want."
But he would not have stopped the attempted coup in January this year if the three or four cabinet ministers involved had gone through with it.
Mandelson is brutal about Brown's personality traits. "Gordon post-1994 is not the man that I knew for at least 10 years before 1994. In the aftermath of John Smith's death and Tony becoming leader, Gordon went to a dark place that was defensive, did not make friends easily, saw people repeatedly out to do him when no such threat existed. He was backed into that corner with some poor advice given by people who surrounded him and who were too sectarian. They reinforced his defensiveness, his fears and his aggression rather than countered them to overcome them. Therefore the Gordon I saw during the period of the Labour government was more often than not an unhappy and an aggressive man, rather than the alliance builder and team player that I had worked with previously.
"I think this left a scar … that I hoped I could remedy, and help him operate in a different way. I did so only at the margin, but I wish I could have done much more for him. There was something about Gordon – he almost had to believe you were only on his side and agree entirely with him to be seen as loyal. Sometimes true loyalty comes from disagreeing.
"I remember Paul Dacre saying to me, 'Gordon is a great man but he has two problems. One he is not on the same wavelength as middle England, and the other is that he is incredibly stubborn'."
He also found Brown when at No 10 unable to organise things to a conclusion. "What I know about government is that if you think something is really important, you really have to get behind it, an announcement is precisely that, you have to have people following it through, forcing through the pace of change and new policy. That is a lesson about government and reform that was not properly applied in our last two years of office.
"What Gordon brought to government was a very fertile mind, very receptive to new ideas, a unique force majeure when he wanted to prevail. But if you really want to bring change, you have to focus on it, you have to follow it up over months and years, not days and weeks. As a result it all became too tactical and too transient." He said Brown simply could not get top-quality people to work for him at the highest level at No 10. "At one point I said to his principal private secretary, Jeremy Heywood, 'Why are there not better top-level people?' The answer was that he could not get people to work for him."
Much of his two years was spent battling with Brown to recognise the recession was changing the public spending landscape. Like James Purnell, he argued in 2008-09 that the crisis meant the government had to launch a fundamental spending review, an opinion backed later in a different way by Yvette Cooper. "Rather than approach it in a crisis-driven way, top-slicing budgets, we needed to rethink how we financed the public sector, draw on private as well as public sources, and drive further reform. There were few takers for it. We got locked in the worse position.
"The problem was that Gordon thought he found an alternative, the reinvention of government using the internet. We all signed up to it, but nobody really believed it would deliver much change and frankly it quite simply petered out after the first announcement. He saw it as a really big thing.
"By the end our policy and message became very statist. There had to be a government programme as a response for everything."
As to the future, "I don't think I can represent the party on the front bench or be a member of the shadow cabinet. I want to make a bigger financial contribution and link it to the training and development of new staff in political campaigning and communications.
"There is a huge amount of knowledge we have generated over the past two decades and we need to marshall it, codify it and pass it on to a new generation. We have to rethink the technology we use, the mode of communication, the system and how it is used locally in a transformative way."
As for the Liberal Democrats, "they have become more Catholic than the pope in embracing Tory policies and Tory prejudices. They will pay a big political price for that, but equally we have to understand that politics may not revert to the conventional two-party system, so we may need their help to form a progressive government in the future."
Somehow, if that day ever comes to pass, Mandelson – now just 56 – may yet be part of that project. The Comeback Kid is nothing if not resilient.
