The demanding duties that fall on those who must deal with the death of a world statesman had an added, most delicate element in the case of Francois Mitterrand.

On a crisp January morning in 1996, the French president's driver was stationed at the door of the politician's extraordinarily humble abode to deal decorously with the line of mistresses wishing to view the remains of the man who had loved them and France in an erratic, often self-serving but eternally passionate manner. Philip Short declares that the driver, Pierre Tourlier, knew all the secrets of a singular Frenchman who journeyed from the Right to the Left, who worked for Petain and fought for the Resistance, who lost his Catholic faith at a young age but prayed constantly.

It is an unusual but forgivable stutter from a biographer whose judgments are shrewd, based on prodigious research and marked by a humane wisdom. Tourlier knew the women, the venues of trysts and even the humour, good and ill, of his employer, but many of Mitterrand's secrets were interred with him. It is one of the major attributes of a fine biography that Short accepts this reality throughout a work that maintains its considerable power for all of 600 pages.

Mitterrand was president of France for 14 years and, with Charles De Gaulle, he was the recognisable face and character of the country to the outside world. Of course, he was unlike De Gaulle in every facet except their shared fascination with power and how to hold on to it. As Short writes: "Mitterrand was a sensualist, an aesthete, a bookworm, a quicksilver, passionate man, by turns reckless and prudent, passionate and withdrawn, calculating and intuitive, gifted with unusual intellect and political acumen."

His ambiguity can be further signified by two other factors: how he lived his private life and how he approached his death. His marriage to Danielle lasted until the grave but Mitterrand spent most of his life with his "second family", his mistress Anne and illegitimate daughter Mazarine. There were countless other liaisons with women. He approached his death from prostate cancer by living in what could best be described as a monastic cell, yet his final meal was of ortolans, a protected species of birds, that were pan-roasted in Armagnac.

The brilliance of Short's biography is not that he tries to make sense of this complicated, difficult yet inspiring man. It is that he accepts that full disclosure, irrefutable judgment and precise assessments are impossible when dealing with any life, perhaps most especially with one such as Mitterrand's that was lived in demanding, unprecedented times. This realisation does not tempt the author to skimp on research. This is a full, frank and annotated life. But Short presents the evidence smoothly and stylishly and only casts a verdict when the evidence is strong. Mostly he tells a marvellous story and points the reader towards justifiable conclusions.

The political sections may test the stamina of those whose interest in the machinations of the French legislature is limited, but they become compelling because they reveal Mitterrand essentially as a man of ideas rather than ideology, as a leader rather than any committed follower to the diktats of party.

A mark of his intelligence was his flexibility of thinking. A sign of his ambition was his ability to switch directions dramatically. Famously, he worked with the Petain regime that collaborated with the Nazis but joined the Resistance. The former may have been forced upon him but the latter proved a launching pad to political power. Similarly, his journey from a middle class, moderately rightist family to the most powerful left-winger in the country was made quickly, with some expediency but with full, enduring commitment.

He, too, was involved in a series of affairs, not all physical. He almost certainly agreed to a faked assassination attempt to raise his profile, he knew of the torture of Algerian dissidents, he was aware of the Rainbow Warrior operation by French security forces that led to the death of a photographer, he was involved in widespread wire-tapping. He also did not tackle the rising inner-city problems that continue to beset France. Yet he died poor by the standards of a life-long politician and his political legacy is substantial. He was strong and correct on the nuclear deterrent, he was tolerant if suspicious of German reunification and was pragmatic on European union.

He was 65 when he came to his full power yet he wrote in 1945: "I am lying in wait for the future." This ambition was finally rewarded with leadership of his nation, but it took a toll of a man whose capacity for intimacy was restricted to the physical. "I have never felt the need to open myself to other people," he said as a young man. In a turbulent life, full of inconstancies and infidelities, he held on to this reticence as an article of faith.

He died as an agnostic but accepted the funeral rites of the Catholic Church. "I have a mystical soul and a rationalist brain," he said, "and I am incapable of choosing between them." He also once admitted: "I work in shades of grey." This produced a life of blinding colour that Short has captured in that wonderful, intangible and compassionate realm beyond the black and white.