As a teenager, Antonia Fraser - then Pakenham - used to recreate the scene in which Mary Queen of Scots was executed.

She, of course, played Mary, sorrowfully declaiming " Pray for me, good Gentlewomen", before laying her head on the block. "My dramatic skill frequently brought tears to my eye," she writes, also noting that her long-suffering cousins, cast in the role of the Four Marys, were more likely to dissolve into giggles than weep.

Fraser's childhood passion for the tragic Scottish queen was sparked by a precociously early love of history, itself the product of her being able to read by the age of four. Her first teacher was her mother, the political activist and writer Elizabeth Longford, and it was perhaps to test the proud mother's claim that her first-born was an avid reader before she was of school age that an aunt gave her a copy of Our Island Story, H E Marshall's history for children.

It was here that Fraser found a painting of Mary that was to influence her life immeasurably. Not only did it inspire a life-long fascination with history - on her first marriage, her head-dress was modelled on Mary's - but her interest in the queen led to her writing a biography that is still in print worldwide. This work not only made Fraser's name, but in some ways reclaimed - and certainly helped revivify - that of Mary too.

Fraser's title for this memoir (My History: A Memoir Of Growing Up), which takes us to the publication of her career-making biography, puts the emphasis on history, because that is the thread on which her life has been strung. Its importance to her cannot, it seems, be exaggerated.

The eldest of eight children, born in 1932 to the Anglo-Irish aristocrat and academic Frank Pakenham, Fraser was introduced from an early age to the family's historic piles, among them Pakenham Hall and Dunsany Castle, both in Ireland, where her imagination was set alight. In this she was a kindred spirit with another of her early heroes, the historian Thomas Babington Macaulay, who "once declared that 'the past is in my mind soon constructed into a romance', something with which I could easily identify."

Fraser's account of her lively upbringing reads like chapters in a novel by E Nesbit. The Pakenham household in Oxford was understandably chaotic, with so many children. Added to this was her father's unworldly, loveable personality.

A don at Christ Church, he switched allegiance from the Tories to Labour, standing unsuccessfully for parliament, but nevertheless managing to get into the House of Lords, a rare animal as a titled Labour supporter. He also was an assistant to Sir William Beveridge, when he was writing his ground-breaking welfare report.

As Fraser confided to her diary, "Very exciting! Dada is going to abolish Want." Of that august figure's appearance as a guest at their table, she recalls: "one got the strong impression that Sir William would have been far happier entertaining Want itself than facing the fairly graceless children of his assistant."

Dramatic changes of direction seem to have been a family trait, as the Pakenhams converted to Catholicism, much to the delight of their daughter, who now could identify even more closely with the flame-haired Scottish monarch. Before then, however, she had enjoyed the unusual privilege of a boy's education at The Dragon School in Oxford.

One of only a handful of girls, she thrived on its intellectual rigour - and also on its fondness for rugger, an activity which she seems to have relished. As a consequence, by the time she was sent to boarding school at the age of 12, "I was not really a girl at all at this point." It was probably one of the few occasions in Fraser's life where she was out of her depth. Brainy and better schooled than her peers, she was ahead of them intellectually but in more worldly respects lagging far behind. The result was social purdah, an experience that clearly still stings.

The picture Fraser draws of her home life and schooldays are the most beguiling of the book. It is like entering another world, her mother as eager to stand for parliament as her father, and the pair working tirelessly for the socialist cause while continuing to live by the standards of the landed gentry.

Despite her father's title, however, there was never, as Fraser recalls, much money to spare. This does not seem to have troubled her much, although she writes, with regret, "Of course, we were never hungry, unlike most people in the world; on the other hand the modern attitude to food, the thrill of cooking, the zest of it all, never remotely touched our house during my mother's long life."

War-time Oxford is vividly evoked, as is the inner life of a clever young woman who, by her own admission, "lacked seriousness". Apart from her voracious reading of history and romance, Fraser was frankly frivolous. A beautiful girl, as the photos here prove, she was keen to enjoy life, and her account of her excitement and stratagems on "coming out" reads like an episode from the Georgette Heyer novels she devoured.

Indeed, as she grew up, romance briefly vied with history for her affections. From the peers' family gallery in the House of Lords she hoped to spy a future husband, and she confided to her diary the attributes she was looking for: "Mine must be Catholic or convertible, a peer if possible, clever, intellectual and literary, interested in his surroundings. Either Labour or amenable, having a house in town and ancient family seat, fond of children and wanting them... Also wealthy and tall."

Later, after graduating from Oxford in history, working in publishing, and marrying the Scottish Tory MP Hugh Fraser, she would admit that her love of Barbara Cartland novels helped her learn how to write her books. It is the sort of comment that only someone with Fraser's irrepressible confidence would dare utter.

That chutzpah is the hallmark of this memoir, her cast-iron self-belief as much a factor in her success as the privileged upbringing and education she enjoyed. At times she is startlingly smug, at others quite willing to laugh at herself. The combination is unusual, and at times amusing.

While the work flags towards the end, as the lists of important names she mingles with grows tedious, the fact remains that Fraser was earning a reputation that most writers would envy. A mother of five by her mid-thirties, she was also an acclaimed popular historian. It was a remarkable feat, turning a woman who might have been fodder merely for society magazines into a doyenne of the review and commentary pages instead.

My History: A Memoir Of Growing Up by Antonia Fraser is published by Weidenfeld & Nicolson, priced £20