Despite increasing frailty, Mr Mandela, who relies on a stick to get about and refers to himself as an “octogenarian pensioner”, has lost none of the charisma and campaigning zeal that have made him a household name.

The former President, who led his people to freedom after serving 27 years in jail, but insists his greatest regret in life was not becoming heavyweight boxing champion of the world, will be spending his birthday at his home in Johannesburg with his 30 grandchildren and great-grandchildren.

The celebrations will start in earnest tomorrow with the arrival of Bill Clinton. The former US President will give the inaugural Nelson Mandela Lecture, established to throw the spotlight on the most pressing social and economic challenges facing mankind.

Royalty, presidents and Hollywood celebrities will later join Mr Mandela, who is known affectionately to South Africans as Madiba, his Xhosa clan name, for a sumptuous, 1,600-seat banquet, which will be broadcast live to an estimated two billion people around the world.

Guests are rumoured to include Queen Beatrix of the Netherlands, Barbra Streisand, Michael Jackson and Oprah Winfrey. But no one knows for certain because the organisers have threatened to sue anyone who spoils the birthday bash by revealing the guest list.

Mr Mandela will be accompanied by his wife, Graca Machel, the former guerrilla fighter and widow of Samora Machel, the late President of Mozambique. He is expected to use the occasion, employing his customary moral authority, to urge world leaders into greater action over the HIV-Aids pandemic and the plight of the world’s poor.

The festivities have been arranged to honour the man and his achievements, particularly his belief in racial reconciliation, which played a central role in avoiding the bloodbath many feared would accompany South Africa’s transition to black majority rule.

Born on the banks of the Mbashe River in Tembuland in 1918, Mr Mandela, the great-grandson of a powerful Thembu king, was groomed to be a leader. But it was Walter Sisulu, one of the giants of the African National Congress’s decades-long struggle for freedom, who drew the impetuous and often autocratic young man into national liberation politics.

After he was sentenced to life imprisonment in 1964 for conspiring to overthrow the apartheid regime, Mr Mandela was sent to the Robben Island prison fortress where he spent his time breaking rocks and furthering his education. It was here that he learnt Afrikaans, the language of his oppressor, which gave him his insight into the fears of the white man.

Mr Mandela’s crowning achievement was to bring together a series of disparate influences. He reconciled the premium placed on umbuntu, or community, in his own African heritage, with the values of democracy and human rights espoused by foreign liberation movements, to forge an exemplary vision for all of humanity, an achievement unique among African leaders.

During the 27 years he spent in prison, the African continent had been liberated from colonialism. Mr Mandela came to power in 1994 after South Africa’s first all-race elections, fully conscious of the enormity of the South African experiment in racial reconciliation and humbled by the fact that he was its symbol. It proved to be an epic journey.

Tributes to him were already pouring in from across the world yesterday. Telkom, the South African telecommunications giant, hopes to route the highest number of telephone birthday messages to be received by an individual. It has provided 100 ISDN lines, which can handle 3,000 calls simultaneously. Wellwishers from outside South Africa can call 00-27 1262 63352 to wish Mr Mandela a happy birthday. Proceeds from the calls will go to the Nelson Mandela Children’s Fund.

The celebrations reach a climax on Sunday with the inauguration of the Nelson Mandela Bridge, a multi- million-pound, 937ft (286m) cable suspension construction at the forefront of attempts to revitalise Johannesburg’s decaying central business district. It will transform the skyline of South Africa’s commercial capital.

Despite unconfirmed reports of renewed ill-health after the discovery of prostate cancer two years ago, Mr Mandela will continue fundraising for his favourite charity, the Nelson Mandela Foundation. He has a formidable reputation for bullying corporate South Africa into donating money to build and upgrade rural schools.

He will be ably assisted by Zelda la Grange, the formidable personal assistant responsible for managing Mr Mandela’s affairs and public profile.

An Afrikaner, and single, she began her career as a government typist at the Department of State Expenditure before landing a job in the Office of the President, where she was promoted to private secretary.

When Mr Mandela stepped down as President in 1996, Ms la Grange, who by this time had acquired a reputation for giving 200 per cent of her time and effort to get the job done, was asked to accompany him to the Nelson Mandela Foundation. She is highly protective of her employer, who calls her darling. She once tried to stop a street artist from painting and selling pictures of the living legend.

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