Alastair Campbell, No 10 Spin Doctor, once dubbed the real Deputy PM, is to release his diaries but not until Tony resigns as, and I quote him, "I would consider it wrong to publish in a manner or at a time detrimental to the interests of the government or the party I served". This suggests sole focus will be on Blair and some material may be controversial, mind you the same was said of Lance Price's 'The Spin Doctor's Diary'.
However this is argued to be of greater concern for Brown. If we are to believe the media, Brown and Blair spent most of the 'Campbell years' in open warfare, Brown hated Blair only slightly less than he hated Campbell, and Campbell's role was to shore up Blair's position. If his diaries do reveal this backdrop it could seriously undermine Brown, particularly if Campbell biases his commentary, but think of the image it gives British politics. The PM and Chancellor were busy briefing against one another while god only knows what else was happening in the wider nation or world - there's something to encourage trust in government.