By any standards this is an excellent biography: insightful, well-written and judicious. Although clear-sighted and honest about the character flaws of Britain greatest 20th century peacetime prime minister, Jonathan Aitken does not hide his personal admiration for his subject’s considerable strengths, nor his affection for her. Although almost 700 pages, excluding the bibliography and the index, the author handles the particular details of her eleven and a half years as prime minister with a lucid commentary and pace that keeps the reader always immersed in his narrative.

All I had known of Aitken’s own life before reading it was his three-year period as the boyfriend of Carol Thatcher, Margaret Thatcher’s daughter, and the publicity given to his later travails with British justice. Thus his biography comes as a pleasant surprise: full of perceptive snapshots of the personalities that dominated Whitehall during Thatcher’s tenure of office, solid judgements, humour and piquant phrases. Most important, it gives a reader who has only absorbed the divisive or dramatic headlines of her political career, a clear and coherent base with which to understand and estimate her personality and her historic legacy.

In his prologue, Aitken records his long association with Thatcher (whom he first met aged 23), not just his time as a regular household guest but as a longstanding MP, the good friend of some of her close political colleagues, and as someone who observed her from the time she became leader of the Tory party in 1975 until the end of her life. Thus he has solid credentials for his opinions and assessments. Although he describes himself as an “unimportant spear carrier” – true in the sense that he never held an important office of state or was part of her team working out the Conservative policies that brought her triumph – Aitken has the intelligence and inside knowledge to write a biography that provides as good a key as any to the extraordinary woman that is his subject.

On her early, formative years he does not provide new information than has already been produced by Charles Moore in Volume 1 of his official biography, but he is very good at summarising the characteristics that propelled a provincial girl from Grantham, and from a very modest household, to the pinnacle of political power: the material austerity, the determination for self-improvement, the patriotism, the influence of her grocer father, a strong-minded Methodist lay preacher. Of her schooldays Aitken writes of her “remarkable capacity for hard work and a granite determination to overcome the obstacles in her way.” At Oxford, she was very serious, intense and competitive, yet also deeply interested in clothes (her mother was a skilled seamstress) and always neatly and fashionably turned out. This never changed. Her dresser when she was prime minister commented on her unerring sense of what suited her and how dramatically she could thus present herself.

Early on a fellow parliamentary candidate, Edward du Cann (later tipped to follow Edward Heath as premier) described Thatcher as “strikingly attractive, obviously intelligent, a goer.” He also observed that she was pushy and overbearing. These two aspects continued to mark her style when leader. Indeed, without being “pushy and overbearing” she would never have reached her goals in the male-dominated sphere of Westminster. As the MP for Finchley it was clear that she was “always driven by ambition”, making an outstanding maiden speech in Parliament in 1959, when she spoke fluently, authoritatively and without notes.

Watching the family at first-hand, Aitken could see they were very fond of each other but also dysfunctional; the household was run efficiently – Denis Thatcher’s money as well as his devotion to his wife helped here – but everything was geared to Thatcher’s absorption in politics. Her parliamentary career came first and her family second in her list of priorities. For her time, her sex and for the Conservative party itself, her devotion to politics was highly unusual. It says much about the difficulties she had with her colleagues later on, and her singular achievement in becoming the first woman to lead the party as well as the first woman to become prime minister.

Aitken provides sympathetic portraits of those who helped Thatcher in the early years, educating her in her political outlook, Sir Keith Joseph in particular: “He was a sensitive, deep and intellectually brilliant Fellow of All Souls, Oxford. She was pugnacious, full of simple certainties and shallow in her knowledge of the legislative process. But they bonded.” It is stirring to read of the events behind her bid for Tory leadership, her bravery in standing against Edward Heath, the incumbent, and the important support of her campaign manager, Airey Neave. He had escaped from Colditz Castle during the war and was thus “well versed in the tradecraft of deceiving the enemy.” Aitken believes this first victory was rightfully won: “She was the bravest, the brightest and the best of the candidates. She deserved her victory.”

The political philosopher Edmund Burke had written nearly two centuries before, “One man with conviction makes a majority.” It was Margaret Thatcher’s conviction politics that helped in her success. As Nigel Lawson, one of her chancellors of the exchequer, was to remark much later and with evident incredulity, “She means what she says.” The British public understood this and applauded her for it, even as it caused devotion or distrust among her cabinet colleagues.

Aitken is even-handed about Thatcher’s faults of character, as well as her strengths. She could be a bully, hated to apologise when she was in the wrong, was often domineering and sometimes rude. She also made the mistake, which led to her eventual downfall, of criticising colleagues in cabinet meetings in front of their peers. Sir Geoffrey Howe, at first so sympathetic a colleague in bringing about the success of her economic policies, became the victim of these attacks and it was his devastating resignation speech as Deputy Leader which was to trigger her own tragic and humiliating departure from office.

Enoch Powell made the shrewd observation that Thatcher never really understood cabinet government; women, he felt, were not really team players; she was a “Lone Ranger”. As a woman she was always outside the clubbable side of Westminster; she had no hobbies, no hinterland, no close friends, no understanding of holidays. This helped to make her a formidable personality in pursuit of her objectives – “she had the character to stick to her guns” – but also a lonely and vulnerable figure, even as she seemed to triumph on the world stage, especially in her relationship with Reagan and Gorbachev, the American and Russian leaders. Her biographer sees they key role she played in helping to bring the Cold War to an end as one of her finest acts of statecraft.

Aitken also details the “extraordinary qualities of energy, courage and determination to change Britain” that should be seen as one of Thatcher’s greatest domestic achievements. He sees the Falklands War as her finest hour on the home front, showing her respect for constitution propriety, her commitment to redeeming her country’s national honour and her personal courage in leading from the front, in the face of most of her colleagues’ misgivings and doubts.

At the end of every chapter Aitken provides a “Reflection” in which he summarises the events of the chapter and draws conclusions from them. It is a very effective way to make sense of a mass of material as well as providing a developing perspective on the whole trajectory of Thatcher’s career. He is clear that she finally fell largely through her own fault. Her cabinet colleagues betrayed her – but this had come about because of the gradual metamorphosis in her behaviour, summarised as “from Grantham to grandeur” and from “humility to hubris.” Power did not corrupt her in the usual way, but it led her to overconfidence in her own abilities and to a highhanded attitude towards those who criticised her. In her third term of office (but apparent in the second) she would divide and rule and hog the limelight when teamwork and creating a loyal cabinet was essential. It was her tragedy that “she often reached the right judgements but enforced them the wrong way.”

Aitken’s judgement remains balanced as he describes the coup that unseated the leader he admires so much: “Depending on your point of view, Howe had either given an unpopular leader her deserved come-uppance or he had committed an unforgiveable action of malicious insurrection.” He himself makes no bones that whatever one might have thought of Thatcher’s arrogant behaviour, “there was no justification for staging a coup against a sitting and three times elected prime minister.”

Thatcher’s years out of office, despite her continued, energetic and successful support for Britain’s interests overseas, “were utterly unfulfilled by retirement.” As Charles Powell, a close associate said after her death, “She never had a happy day after being ousted from office.” This book explains brilliantly why this was so and why so extraordinary and great a career in many ways was bound to end in tears. It is an important addition to the bibliography.

Francis Phillips writes from Buckinghamshire, in the UK.