George Osborne: The Austerity Chancellor, By Janan Ganesh

If you are depressed by the thought of David Cameron as a privileged, overpolished careerist with no convictions, you'll save yourself a lot of distress if you give a wide berth to Janan Ganesh's biography of his Chancellor and closest political friend, George Osborne. That is not to say that Ganesh's book isn't well researched, thoughtful and full of nuggets buried in the smoothest of prose.

Born five years apart, both men come from loving, comfortably-off families, were late developers, showed an early, obsessive enthusiasm for political history, went to Oxford, avoided the Oxford Union, slept around a bit, enjoyed a brief formative spell in the US, worked for the Conservative Research Department, emerged, hugely ambitious, into national politics comparatively unimpeded by doctrine, and were blooded by a notorious political crisis – Cameron by Black Wednesday, Osborne the BSE debacle.

Yet, as Ganesh skilfully shows, Osborne's heritage – Notting Hill, St Paul's, a mother who works for Amnesty, a father with an ultra-fashionable shop in South Kensington – is much more that of the metropolitan sophisticate than Cameron's. The self-possession of Osborne, a "rambunctious boy ... up for anything", a friend remembers, can be seen in his insistence, at the age of 13, on changing his name from Gideon to that of his Military Cross-winning grandfather. "It is of a piece with his character … he ploughs his own furrow," says a schoolfriend.

If the caricature of Cameron is unfair, the Osborne portrayed by Ganesh, a long-standing admirer and now Financial Times columnist, is of a man unashamed to see politics as a profession as much as a means of changing the world. It is not until page 260 (of nearly 300) that Ganesh has a stab at identifying Osborne's convictions. Osbornism, if it exists, is schools reform, fiscal conservatism, cultural liberalism and an interventionist foreign policy.

In an unofficial book such as this, there will always be a trade-off between getting access to the subject and a willingness to criticise or chase uncomfortable truths. Generally, it's a path Ganesh treads deftly. It turns out, wouldn't you know it, that George was responsible for some of the most brilliant phrases in recent political history. And Ganesh is sometimes needlessly generous to our man.

The book lacks revelations on his domestic life and those sagas that have tripped up Osborne (the Mandelson/Deripaska affair in Corfu, his assiduous courting of the rich and famous, not least the Murdoch regime, the truth about the allegedly druggy dinner with a dominatrix), but the picture that emerges is not wholly flattering. Osborne's prodigious political brain is a given, as is his drive, humour, willingness to work hard and pragmatism. But there's a "cold, dispassionate guile" in this "least sentimental of politicians" whose bloodless calculations can make him too clever by half.

Since the book was started, when Osborne was still Cameron's likeliest successor, he has continued to preside over a struggling economy and been booed at the Olympics. He is, though, not a man to be written off. This book amply shows why.

James Hanning co-wrote 'Cameron: Practically a Conservative'