This is a story that derives its drama from the context: the plot is terrific, but is the chief protagonist quite up to it? A good needlewoman in an era of consummate needlework, a poor politician in an era of consummate statesmen and women - notably the incomparable Elizabeth I (Gloriana was not going to lose her throne for love). John Guy, in his lengthy biography, eschews so firm a verdict and attempts a balanced reassessment of the polarised views about Mary Queen of Scots that were so much a feature of her own lifetime and have been ever since.
The romantic view is fuelled by the bare bones of the story.
Queen of Scotland within six days of her birth in 1542; abortively betrothed to the heir to the English throne in childhood; married to the dauphin of France at 15; briefly queen of France before being prematurely widowed; seven years of rule in Scotland, marked by turmoil, resulting from - among other things - two calamitous marriages, one to her cousin Lord Darnley, who is first involved in the murder of her secretary, Rizzio, in her presence and is then himself murdered in a plot that includes her new ally and subsequent husband, the earl of Bothwell; military defeat, deposition and flight to England (all before she was 26); and then the best part of 20 years under house arrest, eating too much, plotting, being depressed, becoming ill, before eventually doing exactly the things to ensure posterity found her execution one of history's great tear-jerking set pieces.
What can we say about the woman whose disastrously flamboyant career this is? In youth, at least, it is not difficult to see how she might have been the centre of attention. Tall, attractive and slim-waisted, with a marble-like complexion, a skilled dancer, oozing glamour, always sumptuously dressed, this was a woman who knew how to behave like a queen - an attribute that, ironically, appealed to her ultimate nemesis, her cousin Elizabeth. And one of the joys of Guy's book is to remind us of just how much evidence of her life survives, down to her childhood Latin compositions, today housed in a leather-bound volume in the Biblioth que Nationale in Paris.
The trouble was that she was never properly on top of the intractable political situation in which she found herself. Little wonder that, as she grew older, she became increasingly moody and wore an amethyst ring that she believed had magical properties " contre le melancholie ". For though there are always sounds of laughter, displays of love and moments of exuberance in the grimmest of times in human affairs, we will not begin to understand the drama of 16th-century Europe without focusing on its politics: the ambitions of the two great Catholic monarchies of Spain and France, the factiousness of Scotland's political leaders, the deep insecurities of a flourishing but beleaguered Protestant England and the constant backdrop - the battle for men's souls in a continent divided by religious ideology - that ensured the political conflict could never result in a polite agreement to differ.
Guy tells the story chronologically, with abundant use of Mary's own words.
His views on Scotland of the period will not endear him to some contemporary Scottish historians who have been seeking to question the received view of a tribal nobility happy to manipulate its queen but hostile to the idea of a centralised government on the English model. Mary herself concurred with Guy, finding the Scottish lords "as factious amongst themselves and as factious towards the ruler as any other nation in Europe".
Mary's relationship with Elizabeth, whom she never met, was strengthened by their joint priority in defending the idea of monarchy, tempered in Elizabeth's case only if support for Mary threatened her own monarchy, as it did. Of the threat, Elizabeth's great minister, William Cecil, was never in any doubt, and Mary was no match for the servants of the Elizabethan state, who bribed her staff for details of her menstrual cycle and carefully filed letters saying "I pray you burn this...".
In one respect, this biography is hardly an advertisement for the art of book-making: the illustrations are an opportunity lost. On page 114, the text discusses in detail Francois Clouet's drawing of Mary approaching the age of 18 and the associated panel portrait, but Clouet is indexed only to page 81. And there is no hint that, if you are patient enough, you will find the Hilliard miniature described 40 pages earlier than its reproduction. The varying amounts of information in the captions seem to bear no relation to what the reader might want to know, to what is explained in the text or even to the exigencies of the plate layout. This is perhaps not untypical of similar productions: in an era in which television has helped us, literally, to see the value of visual documentation, publishers' awareness of how to use illustrations remains primitive.
Nor would one go to this book for its style. There are too many "momentous events" unfolding at "breathtaking speed". And there are the weather reports so beloved of popularisers of history ("by all accounts... an unusually damp and depressing morning"). The weather is significant, but not that significant, especially for those engaged in ruthless power struggles.
This is unkind, but important because it distracts from the fact that Guy has written a marvellous book. Its strengths remind us that the writing of professional history is still a relatively new craft, and of just how much there is still to be patiently uncovered or reconsidered on subjects that have apparently been written out.
Dealing with a subject in which the evidence is often bewildering was often tampered with at the time, or even - as Guy shows - misfiled by supposedly systematic 19th-century archivists, he keeps a clear head, correcting chronology, painstakingly comparing the conflicting official stories of Scottish lords, English politicians and Mary herself. This makes for some enthralling history, without the need for further embroidery, as we watch Cecil & Co doctoring documents and otherwise manipulating the evidence. Guy uses his final judgement - "the unluckiest ruler in British history" - to an extent to rehabilitate her. We need not agree, for the evidence he provides allows us to form our own opinion.
Jamie Camplin is publishing director, Thames and Hudson. He is researching a history of the monarchy.
My Heart is My Own: The Life of Mary Queen of Scots
Author - John Guy
Publisher - Fourth Estate
Pages - 574
Price - £20.00
ISBN - 1 84115 752 X