Journalist Bill Keller covered Nelson Mandela's election for the New York Times. He explains why Morgan Freeman's portrayal is spot on

JOURNALIST Bill Keller covered Nelson Mandela's election for the New York Times. He explains why Morgan Freeman's portrayal is spot on

MORGAN FREEMAN has been cast as God – twice – so he evidently he has no trouble projecting moral authority. The challenge of portraying Nelson Mandela, then, was not the size of the halo, but knowing the performance would be measured against the real Mandela, and his myth.

"If we can say any part of acting is hard," says Freeman, "then playing someone who is living and everybody knows would be the hardest."

The role has defeated actors as varied as Danny Glover (the 1987 TV film Mandela) and Dennis Haysbert (Goodbye Bafana, 2007), in vehicles that were reverential and mostly forgettable. But as someone who studied Mandela over three years while he replaced an apartheid regime with a genuine democracy, I found Freeman's performance in Invictus, directed by Clint Eastwood, uncanny – less an impersonation than an incarnation.

He gets the rumble and halting rhythm of Mandela's speech, the erect posture and stiff gait. There is a striking physical resemblance, enhanced by the fact that Freeman, 72, is just a few years younger than Mandela was in the period the film covers. More important, Freeman conveys the manipulative charm, the serene confidence, the force of purpose, the hint of mischief and the lonely regret that made Mandela one of the most fascinating political figures of his time.

The story of Invictus, drawn from John Carlin's book Playing the Enemy: Nelson Mandela and the Game That Made a Nation, begins with the newly inaugurated president of post-apartheid South Africa looking for ways to enlist his fearful white minority – with its talent, wealth, resentment and capacity for insurrection – in the business of governing a democracy.

His inspired stratagem is to embrace the national rugby team, the Springboks – the darlings of the formerly ruling Afrikaners and, for most non-white South Africans, a symbol of brutal and humiliating repression.

The new president sets the team's captain (Franois Pienaar, played by Matt Damon) the improbable goal of winning the World Cup; the tournament is to be held in South Africa in a year, and the Springboks are given little chance. Mandela sets himself the considerably more improbable goal of uniting country behind the team. So loathed were the Springboks that those few blacks who showed up for matches rooted loudly for the other side. So the rugby campaign was one of Mandela's boldest strokes of statecraft.

According to Freeman, his mission to portray Mandela on the screen began with a public invitation from the subject himself. At a news conference to promote his 1994 memoir, Long Walk to Freedom, someone asked Mandela who should play him in the movie. "And he said he wanted me," Freeman recalls. "So it became. That was the whole sanction, right there."

The South African film producer Anant Singh, who bought the movie rights to Long Walk, arranged for Mandela and Freeman to meet. "I told him that if I was going to play him, I was going to have to have access to him," the actor says. "That I would have to watch him up close and personal."

Their encounters ranged from tea at Mandela's home in Johannesburg to a charity fundraiser in Monaco. But through multiple screenplays, Mandela's sprawling memoir proved too unwieldy for a film, and Freeman abandoned it.

Then, in 2006, Carlin, a British journalist who had covered Mandela in the 1990s, was in the Clarksdale living-room of Freeman's business partner, discussing his book. Afterwards, Freeman sought Mandela's blessing, bought the rights and persuaded Eastwood to direct. (Their two previous collaborations, Unforgiven and Million Dollar Baby, both won Oscars.) They hired Anthony Peckham, a South African migr, to write the script. Freeman insists that if the portrayal transcends impersonation, that is largely Peckham's doing. As an actor, he says, "you're looking for the physical: how he stands, how he walks, how he talks. Nuances he has in terms of tics or movements. Things that sort of define him. The inner life has to come off the page. Whatever he's thinking, I don't know. The script is going to inform you of everything."

While Freeman brought to the project a decade of first-hand observation, Peckham, who left South Africa in 1981, had never – and still has not – met Mandela. "He was a non-person for my entire growing up," says Peckham. "You weren't even supposed to have pictures of him."

Peckham's main difficulty in writing a script, he found, was to do justice to such a familiar and beloved figure without tipping into idolatry.

"It was extremely difficult, because in the period I write about he was in many respects at his most saintly – leading the country the way he did," Peckham says. The danger of hagiography "was something we all knew was an issue. We didn't want to be offensive and disrespectful either. It's easy enough to kind of show someone's feet of clay if you're prepared to be brutal about it, but not when you want to be respectful without hero-worshipping".

The notion they settled on to humanise the hero was that, while Mandela was making a nation he was neglecting his own family.

"Knowing what I know of Madiba personally," Freeman says, using Mandela's clan name, "his real concern is not for what he did, but more for what he didn't do. He had family obligations that he couldn't live up to."

Carlin, who covered Mandela in his political prime and spent many hours with him, says Freeman "channels Mandela beautifully". Most important, Carlin says, Freeman – abetted by the screenwriter – "impressively conveys the giant solitude of Mandela".

Though an admirer of Freeman, Carlin had seen Mandela done wrong often enough that he braced himself for disappointment. After attending a screening in Paris last month, he sent an ecstatic e-mail message. "They didn't screw it up!" he wrote. "WHAT a relief!" For me, the realisation that Freeman had nailed it came as the film ended. Alongside the closing credits came still photos of the actual Mandela. And for a second I wondered, "Who is that imposter?"

• Invictus is released on Friday. Bill Keller is the author of Tree Shaker: The Story of Nelson Mandela.