The book captures beautifully the extraordinary place Campbell occupied within the Blair government. What we learned from Hutton was that, in summer 2003, the Rory Bremner caricature of a Prime Minister plucking ineffectually at the spin-doctor's sleeve was, in fact, true.
Blair, a better judge than Campbell, tried desperately to hold him back in his fight with the BBC. But the interests and wishes even of the Prime Minister came second to dealing with a supposed slur on his spin-doctor's integrity. This, surely, was the real reason that Campbell had to go.
Yet for all their criticism, and their status as Campbell-baiters, one senses that Walters and Oborne, both politiascal journalists, are like so many at Westminster a little starstruck, a little transfixed by the campbellismo not quite understanding the revulsion it caused out in voter-land.
Campbell was indeed a genius - tactically. He won the daily battle for the headlines. But, strategically, he has been probably the most disastrous occupant of his office in its short history.
Campbell's war against the BBC is only the most recent example. Tactically, with the assistance of Lord Hutton, it was a triumph, winning a wholly unwarranted apology and three good scalps.
Strategically, however, if the aim was to disprove the BBC's story and restore public trust in Blair, it simply could not have been more counter-productive.
Campbell then administered the final coup-degraceless with his notorious Carlton House Terrace press conference on the day of Hutton, ending all hope that the report could benefit the Government and reminding us again how much the whole administration was held hostage to his ego.
More broadly, the overhyping that plagued the first term (£40 billion for the NHS, anyone?) means that even now that New Labour has real achievements to boast about, it is just not believed.
This is essentially, if modestly, a successful government. But it has been brought into undeserved disrepute by its chronically abusive relationship with the truth, a relationship of which Campbell was at the centre.
And then - another thing not really dealt with by the authors - there is this even more ironic and troubling question. Campbell hated and wanted to control journalists. But by orchestrating Whitehall to the media drumbeat, with a daily diet of initiatives, did Campbell impose the values of the Government on the press - or did he impose the values of the press on the Government?