By the time she became education secretary under Ted Heath in 1970, she had established herself as a "crypto-Powellite" standard-bearer of the Right. In the privacy of the Cabinet she often clashed with the Prime Minister, warning him that strikes should be seen as battles "between unions and people, not unions and government". If Heath had heeded her he would never have fought an election on the issue of "Who governs Britain?" When Israel faced defeat in the Yom Kippur war of 1973, Mrs Thatcher told Cabinet that Britain's neutral stance had "lost support of everyone, especially young. Must say no question of Israel being wiped off face of earth." Heath snarled back: "Don't accept [her] view of public opinion. It's a Jewish-inspired press campaign." Her philosemitism began when a Jewish refugee stayed with her family during the war, developed when she was adopted as candidate for Finchley (where Jews made up 20 per cent of the electorate), and culminated in her staunch support for Israel as prime minister despite the Arabists of the Foreign Office. She felt closer in outlook to her Jewish colleagues (and promoted them in unprecedented numbers) than to the Church of England in which she married Denis, but which heartily loathed her. Mrs Thatcher always liked outsiders: she was one herself.

It was her defeat of Heath in 1975 that propelled her unexpectedly into the front rank of politics. The incumbent despised his own party ("shits, bloody shits and f***ing shits") and responded to a challenge by a woman with utter incomprehension. For her part, she warmed to the "grumpy solidarity of the cash-poor upper-middle class, the experience of war and the dismay at the country's steep decline" (Moore) typical of most Tory MPs, such as her campaign manager Airey Neave. Harris is good on the way she impressed her own ranks by "eviscerating" Labour's bullying Chancellor, Denis Healey. For the first time since Churchill, the Tories had a leader who could dominate the Commons, though it was never effortless. 

Long before she entered Downing Street, Mrs Thatcher had generated an intellectual excitement that spread across the Atlantic. Her first US lecture tour wowed everybody from Reagan to Kissinger. At a dinner given by Mrs Graham of the Washington Post, she sat next to Alan Greenspan, later chairman of the Fed, who recalled: "The very first thing she said to me was ‘So, Dr Greenspan, why is it that we in Britain don't have an M3?'" She impressed intellectuals by taking them seriously. When my father, Paul Johnson, resigned from the Labour Party in 1977, she promptly quoted him in her peroration at the Tory party conference. He had, she declared, expressed "movingly and with a writer's clarity" his "attachment to the individual spirit". For her to pay tribute to a former editor of the New Statesman was not what the party faithful expected — but they loved it. Moore captures this intellectual ferment, but also the doubts of a profoundly philistine political establishment. Chris (now Lord) Patten admits that he found her talk of a battle of ideas "a bit rum". Others were much more hostile. That they have always remained so is demonstrated by these two books, not to mention the attitudes that resurfaced after her death.

Mrs Thatcher's premiership was so dramatic that biographers are spoilt for choice. Harris is most informative — though also necessarily least disinterested — in his account of her fall. He does not exonerate her, but he considers Nigel Lawson, Geoffrey Howe, John Major and her other Cabinet colleagues to have been much more short-sighted, particularly on Europe, than she was. He also thinks they were more devious. He is especially keen to skewer those on the Right who plotted against her, such as Norman Lamont, or those in her team who panicked and let her down, such as Kenneth Baker. One topical reminder is that, just before she was brought down by Michael Heseltine, she promised a referendum before sterling could be abandoned in favour of what would later become the euro. That principle — which then shocked even her most loyal supporters, such as Cecil Parkinson — almost certainly saved the nation from the chaos that engulfed the eurozone 20 years later.