The Alastair Campbell Diaries, Volume Two: Power and the People 1997-1999, By Alastair Campbell

Why would anyone want to read yet more memoirabilia of the Blair government, unless they have a professional interest in the stuff?

Here is the second of four volumes of the unexpurgated edition of Alastair Campbell's diaries, which, together, will be roughly four times the length of the edited version published 12 days after Tony Blair left office in 2007 saying: "That is that; the end".

Since then we have had memoirs from nearly everyone who worked at No 10, or who is married to someone who worked at No 10. Each time, the central story of the New Labour years, that of the relationship between Blair and Gordon Brown, becomes more awful. Surely we have got the picture, in all its dysfunctional weirdness, by now?

Well, no. The difference between memoirs and diaries is in the name. It is the difference between memories and a record of what happened day by day. Blair, looking back, imposes a sense of purpose on his "journey" that was probably not always evident, even to him, at the time. Peter Mandelson, in what Campbell here calls his "insufferably self-indulgent account", retrospectively smooths the joins in the improbable tale of his casting out from and recall to the centre of power.

And we have to remember that, in an inversion of usual practice, Campbell edited his diaries for early publication to cut out some of the most interesting bits. Much of what is now revealed concerns the appalling behaviour of Brown and his faction bosses – and even though Blair has stolen some of the thunder on that, the psychological case study still has the capacity to surprise. Campbell finally reveals that it was he who was, after all, the source of the famous "psychological flaws" description of Brown – an entirely accurate, but unhelpful, description of the Chancellor whose deluded grievance that Blair had stolen the leadership from him had surfaced in a book in January 1998.

The following month, Campbell found himself seated next to Sarah Brown at a Chequers dinner and told her that her husband's "colleagues hate him because he allows this briefing against them the whole time"; that Charlie Whelan, Gordon's press officer, was responsible for most of the government's media problems; and that Ed Balls, Brown's economic adviser, was "not fully grown up". Sarah was reduced to saying "I didn't realise you felt so strongly" once or twice. In other words, as reported back to Campbell by Anji Hunter, Blair's gatekeeper, via Sue Nye, Brown's gatekeeper, it was "war".

In a story threaded with strong women, Fiona Millar, Campbell's partner, "thought it was pathetic that TB could not stand up to GB" and force him to sack Whelan, whom Campbell describes as the "grinning clown sitting in the corner" of meetings. The bigger question, we can see clearly looking back (althought it was not obvious at the time), was why Blair did not sack Brown. Interestingly, Campbell attempts to answer that in his introduction: "Even with the benefit of hindsight, it is not entirely clear that TB could or should have moved or sacked Gordon."

The real value of the "complete" diaries, though, lies in their total immersion in the fierce urgency of the present tense. At the time, Brown's "crazy" sense of grievance (Blair's word) was just part of a madhouse that had to be managed, and Campbell focused on the symptom not the cause, by trying to get Whelan sacked, not his boss. The diaries capture what seemed important at the time, without knowing where it would lead or what was coming next. So, huge issues creep up without historical fanfare, as the author, at the end of a long day, has no idea how important they will seem the next day. The impeachment of Bill Clinton, for instance, is just an off-stage distraction that made the media handling of the bombing of Iraq a more difficult assignment than it otherwise would have been.

That's a moment rich with ironies, as, altogether, Blair stood by a US president confronting Saddam Hussein in November 1997, February 1998 and December 1998. Much more than in the edited diaries, the premonitions of what was to come are striking: there are entries in which Campbell tries to stop the Foreign Office pushing the line that a new UN resolution was needed to authorise military action; and worries from "the intelligence guys" about a terrorist response to the bombing of Iraq – "probably Bin Laden", at a time when his name was virtually unknown.

Campbell is a great diarist, and precisely because he is not a stylist. His is spare, Orwellian prose, compelling by virtue of his position and his narrative "grip" – a favourite Campbell word. Whatever you think of Blair and the Blair years, this is what it was like at the time.

John Rentoul is The Independent on Sunday's senior political commentator and author of the biography, Tony Blair

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