The Mail on Sunday has not seen the book, not due out for some weeks. It may make uncomfortable reading for Brown, but not for reasons given by the Mail.
This technique of saving the most important or revelatory part of the article for the last sentence is known amongst the ladies and gentlemen of the press as the depth charge. Whether this is because of the delay before a depth charge's explosion, or because the revelation is deep in the article, I do not know.
There's also something rather lovely about the authority of the first sentence setting up the apophatic teasing of the second.
Lobby journalists filing an article