Aitken gradually sheds his tribal Tory respect for the party elders as the book continues. He remains aware that Mrs Thatcher sometimes behaved unreasonably and outrageously. His account of Geoffrey Howe's resignation is gripping and puts full weight on the Prime Minister's foolishly dismissive treatment of him. Likewise his description of the leadership struggle, which reads like a thriller, blames much of her defeat upon the fact that she had increasingly lost touch with the backbenchers who had earlier been her fortress of support. And he is harsh in his analysis of the poll tax debacle (though he mistakenly traces its adoption back to her 1970s' commitment to abolish the rates). The poll tax really originated on the Tory Left as a way of avoiding an unpopular rating revaluation. Even so, Aitken increasingly recognises that she wasn't her own worst enemy — there were too many other claimants to the title for that to be true.

And that is where Aitken's insider experience as a well-connected Tory backbencher comes decisively to his aid as an analyst, biographer and historian. He takes seriously the political arguments at issue in the battles between Margaret Thatcher and her senior colleagues — on shadowing the D-Mark and the Exchange Rate Mechanism in her last years of power, and on Maastricht, Bosnia and the euro after she left office. He also sheds fresh light on some of them. He extracted from Nigel Lawson, for instance, an admission that he never directly told the Prime Minister or the Cabinet that he was shadowing the D-Mark until she was alerted to it by Financial Times journalists. Unless there is a misunderstanding here, this is a significant admission. For shadowing the D-Mark was at least a factor in the revival of inflation; the need to impose a monetary clampdown; the undermining of the Thatcher government's reputation as a conqueror of inflation; and her renewed vulnerability on every other political issue.

Together with the consequent dispute over the ERM, it led, finally, to her defenestration and isolation on the back benches and in the House of Lords. Yet when Aitken goes carefully over all these disputes, he concludes (establishes, really) that she was correct — and correct against the main currents of establishment and grandee opinion — on almost every one them. In particular, she fell from power at the very moment when she was realising-very late in the day — that Britain was simply unsuited to the kind of European Union that the other member-states wanted and when the Tory party was rallying to her standard on it. It would be a very Faustian conclusion except that it's no conclusion: other Fausts still line up to be deceived.               

Aitken has written an impressive and entertaining book. It is full of fresh information, clear and readable accounts of the main controversies of her premiership, and good Thatcher stories (many new to me). Above all, it demolishes the fallback anti-Thatcher position adopted since her greatness became impossible to deny. This position — outlined in the Meryl Streep movie — is that Mrs Thatcher won major battles but they arose more from her combative personality than from any wider political necessity. Aitken flirts with that idea, but in the end he rejects it. She was indeed a difficult woman, but she was difficult on Britain's behalf.