THERE'S a moment early in this book where the author . . . in his revised, updated, unsanctioned and trouble-making work . . . writes, "No one of that era (November 1972) would ever label Brown a puritanical Scot with a humourless, wooden face and a grating habit of repetitiously uttering identical slogans." The inference is, of course, that that is precisely what Brown has become to the 2007 reader of Bower's analytical, if not comprehensive tome.

No matter. This well-informed, character assassinating, hatchet job for the airport lounge . . . pages of scurrilously vindictive prose and conclusions, seething in its pointed opprobrium is a true exemplar of the main blood sport legal in Britain today. It remains to be seen whether Labour under Brown can withstand the rising tide of antipathy in nationalist Scotland and depressed England where the Tory-Lite Tendency under David Cameron will seek their first new-millennium parliament in 2009.

But what's clear from sources like Peter Mandelson, the former Hartlepool MP, is that Brown's politically-motivated loyalty compared to his actual alienation from most of the backbench, the Blairites, and the voter, will not sustain him any more than Labour's political-ideological failure did Jim Callaghan when Harold Wilson resigned in the mid-1970s.

What's compulsive here is Bower's depiction of a man that, in his opinion, never achieved his true potential through cowardice and ideological stubbornness with portfolio, lack of political risktaking and certainty to be ruthless for his constituency.

Originally a brilliant, bookish, academic of historical, spiritual, Presbyterian bent he could not make the singular leap to be an instinctual operator like Blair. He lacked the brazen sangfroid to be bold and clinical in the way that Blair did not. Brown's adversary even left Downing St according to his own timetable. Bower deconstructs Brown while giving his target 'a good kicking'.

While the score-settling of these pages is awful and fascinating, there is no illusion concerning Bower's objectivity. This is part of the corpus that Campbell's diaries may well infect further.