Books: The end of the rainbow?: Mandela: the authorised biography by Anthony Sampson HarperCollins, pounds 24.99, 678pp

Denis Judd discovers a pragmatic fixer at work behind the smiling mask of a secular saint

During Queen Victoria's triumphant 1897 Diamond Jubilee parade through tumultuous London streets, Mark Twain shrewdly remarked that the Queen-Empress was the real procession and the rest "mere embroidery". In contrast, some critics of the new South Africa have been grumbling that President Mandela is merely the fancy icing on the cake of a post- apartheid country which seethes with unresolved - perhaps unresolvable - problems, as well as offering a number of glorious opportunities to prove that a "rainbow nation" can flourish and grow.

It is certainly possible to see Mandela as past his sell-by date, and, in any event, simply another African nationalist leader in a whole sequence beginning with Nkrumah and continuing with - among others - Kenyatta, Kaunda and Mugabe. Their ritual and ultimately dispiriting process includes vibrant "Westminster style" opposition, political frustration, violent resistance, demonisation by white power-brokers, imprisonment, release, rehabilitation and installation in office surrounded by representatives of the dissident's former masters. Thereafter, the newly emancipated nation descends into chaos and corruption, and the crushing of those very liberties that the dissident leaders had fought passionately to achieve.

Is Mandela the one to break the sequence? Is he essentially a man of mature vision and endless patience; a saintly figure, busy binding up the nation's wounds while being named again and again as "the individual I most admire" in celebrity questionnaires; or a sophisticated and pragmatic ex-revolutionary, provoking near-universal admiration and trust in equal measure?

Anthony Sampson's authorised biography is warmly to be welcomed, not least because it is more substantial and revealing than Mandela's bestselling autobiography. That might have been entitled Long Ramble to Freedom and, with Vikram Seth's A Suitable Boy, remains possibly one of the most eagerly bought and finally unread books of recent publishing history.

Sampson comes to his formidable task with an advantage that is both enabling and potentially crippling: he is a long-standing intimate supporter and admirer of his subject. He has other less contentious advantages, however, in particular access to Mandela's unpublished correspondence from prison, his memoirs written there, various letters, intelligence and diplomatic sources, and a large number of interviews not merely with Mandela himself but also with many of his friends and colleagues.

Among the scoops that are revealed are several which highlight the ambivalence of Mandela's opponents, black and white, towards him. In 1981, a South African Department of Justice psychological profile described him as the obvious leader within the prison and as possessing the qualities that would make him the leader of the African majority. It judged that he was "a practical and pragmatic thinker who can arrive at a workable solution on a pragmatic basis" and that "he maintains outstanding personal relations, is particularly jovial and always behaves in a friendly and respectful way towards figures of authority". In other words, the South African authorities were already "doing a Kenyatta" and beginning the process of stealthy negotiations with Mandela, which were to lead to his eventual triumphant release and the establishment of majority democratic rule.

In addition, Sampson claims that although Western diplomats and businessmen steered clear of endorsing Mandela before 1990, a year later the tide had turned and he even saw Queen Elizabeth II as a special supporter after their 1991 meeting. As to his apparently warm and creative relationship with F W de Klerk, Sampson argues that not only did Mandela trust P W Botha more, but by the time he and de Klerk received the Nobel peace prize they were not on speaking terms - something which, if true, must have made for some awkward moments in Oslo.

There is much else of interest, although some of it has certainly attracted speculation before now. For instance, Mandela was viewed with at worst hostility and at best anxious ambivalence by factions and individuals within the freedom movement. He apparently supported private enterprise from the 1950s, but this inconvenient fact was suppressed by the South African Communist Party during his imprisonment. Within the prison on Robben Island there were bitter and heated debates between Marxist and nationalist leaders over the future policies of a liberated South Africa, and up to the time of his release Mandela was seen by the extreme left within the ANC as contemplating a sell-out.

At one point, it is claimed, Mandela's relations with the South African Communist leader Govan Mbeki, father of Mandela's designated successor Thabo, left them barely communicating. From the opposing angle, it is alleged that British right-wingers, notably James Goldsmith and John Aspinall, encouraged Chief Buthelezi and Inkatha in their opposition to the ANC. At the same time, Sampson does not shirk from pointing out the culpability of the ANC in the horrifying killings that accompanied the painful progress to emancipation.

As for Mandela's years in power, Sampson gives a measured and generally revealing account of the various challenges and tribulations of the new regime - from the struggle to raise the living standards of the majority to the messy unravelling of the highly-charged marriage to Winnie; from the need to stop the economic rot as well as the feared descent into administrative disorder and commonplace violence, to the urgent need to establish international confidence in the new South Africa. We are left with a portrait of an indisputably great man, happily remarried to the feisty and graceful Graca, widow of Mozambique's President Machel. Sampson believes that, under her influence, he is blooming like a flower late in life.

This biography is a great leap forward in our understanding of a man who is both enigmatic and private, yet likes to present himself as a simple country boy made good. It is beautifully produced and reasonably priced, packed with accessible information. Anthony Sampson has carried out his difficult commission with skill and sensitivity, though there will be other, more robust accounts in due course. In the meantime, the prospects of South Africa remain notoriously difficult to predict in the post-Mandela era which arrives next month.

Denis Judd is Professor of History at the University of North London; his latest book is `Empire: the British imperial experience from 1765 to the present' (Fontana)