Spurned Bush wife promises tell-all memoir about 'the family that is a political operation'

It is a prospect to have even those triumphant Bushes quivering with trepidation: a tell-all memoir by a spurned and disaffected family insider of two decades – with a possible helping hand from the queen of poisonous celebrity biography herself, Kitty Kelley.

The dark threat from within comes in the shape of Sharon Bush, the estranged and soon-to-be-divorced wife of Neil Bush, the brother of President George W and of Governor Jeb of Florida, and youngest son of the 41st president, George H W, and his formidable wife, Barbara.

That would be bad enough. But of no less concern to the Bushes must be the revelation by The New York Observer magazine that Ms Bush has lunched in Manhattan and talked at length with Ms Kelley, who has few peers as a destroyer of lofty reputations.

Frank Sinatra, Nancy Reagan, Elizabeth Taylor and the British Royal Family have already featured among her subjects. Now she has the Bushes in her sights. "I've already done about 716 interviews so far," she said this week, "but I learned a great deal about the Bush family from Sharon." And, it may be safely predicted, not all of it flattering.

Neil Bush figured in the 1980s savings-and-loan scandals as a director of the Colorado-based Silverado, whose collapse cost American taxpayers $1bn (£640m), and has long been a Bush black sheep. He reportedly left his wife for Maria Andrews, a former worker on his mother's staff.

According to the magazine, he offered Sharon Bush only $1,000 (£640) a month in support. When she told him she needed more, his reply was: "Just get remarried." Hitherto, America's most powerful political dynasty has been remarkably successful – whether as a family or as head of ruling administrations – at keeping its dirty linen private.

George Snr never got into the dish-it-out autobiography business, while Barbara is best remembered for the memoirs of her dog Millie. The one insider book so far about the current Bush White House, written by a former speechwriter, is pretty friendly, and not especially revealing.

This one, if it is not merely a ploy to up the alimony, might be different. The word is that Sharon Bush will tell of the influence of the former first lady, Barbara, and of tensions between the brothers.

Sharon Bush's PR is being handled by a former tabloid editor, Lou Colasuonno, whose spiel mixes hype with menace. The author "witnessed the evolution of a dynasty", he gushes. "She believes, and is prepared to reveal, that the Bushes are far more ... calculating than has ever been seen before. She will show that the family orchestrates its public image from top to bottom. She will reveal that the family is in essence a political operation."