Nicola Sturgeon's biography

David Torrance's biography of Sturgeon is the first. As if to ward off the criticisms he rightly anticipates, he writes that it should be considered an "interim biography". Sturgeon did not speak to him, but some of her friends, colleagues and associates did. Out of those conversations - some unattributed, many from other members of the political pack, a cadre not famed for its powers of perception - and from a ream of newspaper interviews and columns over the past 30 years, Torrance has put together a work that reads more like a glorified curriculum vitae than true biography. Those turning to it for a potted history of the fortunes of the SNP since the mid-1980s will not be disappointed. Those seeking insight into the personality of the First Minister will.

Torrance seems well aware of this, and in his preface admits "I make no grand claims for what follows". It is an odd confession, hinting more at a writer determined to stake out his territory and get his excuses in first, than a biographer keen to find ways of fathoming a woman whose depths remain unplumbed by all but a few. Nor does he instill confidence in those of us who were hoping for revelations. In the opening chapter he describes the day Nicola Sturgeon was voted First Minister, when she wore a red "one-piece" dress. Unless he had hoped she would be in a bikini, the word is meaningless. It's a tiny detail, but as any good biographer knows, a single word can be mined for a hidden agenda, and in this instance one's immediate reservations are gradually borne out: Torrance treats Sturgeon with a degree of awe and wonder, but at no time does he allow us to forget that she is a woman. Except, that is, when it comes to discussing the particular issues attached to being a female politician. On that subject he has almost nothing to contribute. He does, however, talk of her "mother-of-the-nation image", another peculiar description that says more about the writer than his subject.

For all these drawbacks, this is a useful and breezily written book for those needing a reminder of the political arena in which Sturgeon has flourished. A happy working-class upbringing in the village of Dreghorn near Irvine saw her turn to politics precociously young, in part thanks to the influence of an excellent modern studies teacher who encouraged his pupils to discuss current affairs, and an English teacher whose Labour credo made her bolshie and turned her towards the SNP. But as Torrance nicely puts it, there was another factor: "Margaret Thatcher served as Sturgeon's recruiting sergeant." As Sturgeon has said, "Thatcher was the motivation for my entire political career. I hated everything she stood for." How ironic that it was Britain's first and much-reviled woman Prime Minister who inspired Scotland's first and highly regarded woman First Minister.

Those of us who find the childhood years of biographies the most enlightening will learn little here. Likewise there is meagre information on Sturgeon's personal life as she grows older. At the University of Glasgow, where her law studies came second to her involvement in the SNP, and in the years thereafter she rose swiftly through the ranks, campaigning for others before standing herself - three times, twice unsuccessfully - for Govan. Torrance makes no more than glancing references to boyfriends during this time. Of Peter Murrell, whom Sturgeon married in 2010, we are told nothing, as if the fact he is the SNP chief executive says all we need to know.

Once on the terrain of the parliament at Holyrood and Sturgeon's pact with Alex Salmond, when he returned to lead the party in 2004, with her as his deputy, Torrance is more assured. This is his natural domain, and he can trade facts, figures, speeches and political motivations with the best of them. But when it comes to anatomising his subject, he seems almost reluctant to probe beneath the surface. All we learn, as any regular newspaper reader already knows, is that Sturgeon has grown more relaxed over the years, has a punishing work ethic, is an avid reader - "a historical fiction geek" sneered Ian Jack in the Observer - and while her exterior has often been chilly, has a warm heart and loyal nature. And she likes high heels. The only thing that shines through from this book, at every turn, is her genuine social ethic, which has been the driving motivation of almost everything she has done. Even then, Torrance casts an unsubstantiated shadow of doubt on the blindingly obvious, on the last page referring to her as "apparently sincere".

Such thin pickings will leave some eager for more. That, however, may be many years in coming. Torrance set himself an almost impossible task in that few politicians are more private, or have had a more focussed career than Sturgeon. There is little dirt to dish, but there will, in time, be considerable philosophical and political reflection, or so one assumes. On those few occasions where there is a trail that could profitably be followed, Torrance neglects to pursue it. Hints, for instance, that there was a problem during Sturgeon's law career are cauterized by quoting her saying "I've got nothing I want to confess". Signs of her changing appreciation of the nature of the political circus, as when she made her famous apology to Holyrood for urging a non-custodial sentence on her constituent, the fraudster Abdul Rauf, and wondered if politicians ought to allow each other more space "to reflect on honest mistakes", are left hanging in mid-air.

In all this, as in the book as a whole, the author reveals his reporting rather than investigative roots. But there is no doubt that Sturgeon is, as a newspaper once called her, "a tough nut to crack". That Torrance has not done so cannot be considered entirely his fault.

Nicola Sturgeon: A Political Life by David Torrance is published by Birlinn, priced £9.99