It's not just awards panels who've been impressed by Idris Elba's portrayal of Nelson Mandela in the new big-screen biopic - Mandela's family, and even the late statesman himself, gave it the thumbs up. The Luther star tells Shereen Low why it was a dream role.

It was an ironic twist of fate.

Hours after Idris Elba walked up the red carpet for the UK premiere of Mandela: Long Walk To Freedom, it was announced that Nelson Rolihlahla Mandela had died.

Elba, who portrays the late South African President in the film, issued a statement saying: "I am stunned at this very moment. We have lost one of the greatest human beings to have walked this earth, I only feel honoured to be associated with him."

Ironic timing aside, taking on the lead role in Justin Chadwick's drama was always set to be huge for the actor.

Already known for playing troubled detective DCI John Luther in the BBC series and drug kingpin 'Stringer' Bell in US show The Wire, 41-year-old Elba's now making his mark on the world stage and his performance has met with awards buzz - so far, he's up for a Golden Globe and a Screen Actors Guild award. He's also hotly tipped for a Best Actor nod at the Oscars (nominations are unveiled on January 10).

But, he says, this wasn't on his mind when he signed on.

"If I'm really honest, every role I make, I feel like I put my work in. It's on someone else to say this is career-defining, and I take that as a compliment, but ultimately I try and work hard in every role I do.

"But would I like an Oscar? Yeah man!" he adds, with a deep laugh.

Mandela: Long Walk To Freedom, adapted from the late statesman's autobiography of the same name, spans Mandela's journey from his early years as a herd boy in rural Transkei to a lawyer in post-war Johannesburg, through to his 27-year-long imprisonment and inauguration as the South Africa's first democratically elected and black President.

It also focuses on the changing relationship between Mandela and his second wife Winnie, played by Naomie Harris.

Elba admits he didn't take Chadwick seriously when he was initially approached for the role, which Denzel Washington was originally earmarked for.

"I didn't really believe him to be honest. I thought it was a joke. I thought, 'What? Who? No! Really?'" he recalls.

Then, the reality of who he was about to play sunk in.

"It is very daunting. It was a massive undertaking, but it was a gift of a part. I don't look anything like Mandela. To play someone who is great, and to have the whole 52-year span to play the character is a gift, so I really enjoyed that," he says.

"South Africans weren't allowing me to lie and pretend or mock this role. That was what made my challenge even harder. Ultimately, it gave me a real benchmark to work towards."

But Elba never had any doubts about whether he could do it.

"I had the conviction of Mandela behind me. His story is so amazing. If he could live that life, then I could make his life on film."

While he never actually met Mandela, Elba won over the former President and his family, including his ex-wife Winnie and two of his daughters, Zindzi and Zenani, who gave their backing to the film.

"Winnie's amazing. She calls me 'Husband'," says the London-born actor with a smile. "Winnie, Zindzi and Zenani have been really helpful from day one. Winnie's very insightful about how she wanted to see this film come to life. She had seen loads of films about Mandela and she wanted the real Mandela, the real depiction of her family on screen."

So what's their verdict?

"They love it," Elba says. "I've seen it with them twice now. They are very moved by it, it's very personal to them and there are some high emotions."

Mandela even saw a few clips before he died. ("I think he had been very complimentary about parts of the film he saw.")

Elba, who wore prosthetics and spent four hours a day in make-up being transformed into the older Mandela, admits portraying him at different ages was more challenging than nailing Mandela's unique accent.

"The accent is a continuous progression for me, but mapping out who he was as a young man and who he became as an old man was definitely harder. Justin and I really paid attention to what that looks like, feels like, the age, the incremental moments in his life."

As a father himself, the twice-married actor reveals the prison scenes in Robben Island were particularly harrowing.

"One of the scenes I will never forget is when Mandela is in prison and he finds out his son Thembi has died in a car crash and he's not allowed to go to the funeral. It broke my heart," he recalls. "I've got a daughter myself [Isan, 11] and if anything was to happen and I couldn't get there, I'd be heartbroken, so that was one of the toughest scenes for me."

With further accolades heading his way, Elba's taking the attention in his stride.

"For the last five years, the level of attention on my life has been like, 'Woah'. I didn't expect it. So I can't imagine it getting any worse or more," he says.

"People know my story, they know who I am. I really want this film to get as much attention as possible because it's a legacy that we should all pay attention to, and there's a lesson within it.

"To be honest, I'm just honoured to have the opportunity to be asked to play such a great man," he adds.

Aside from Luther and The Wire, Elba's appeared in the two Thor films, Guillermo del Toro's Pacific Rim and Ridley Scott's Prometheus.

Often considered one of the world's sexiest men, does he fancy taking on some lighter fare next?

"I'd love to do a romcom. Get me in now! I could do my best Hugh Grant," he says, laughing.

"I'm one of these actors who's not afraid of trying anything and I don't want to be pigeonholed. So romcom, bring it on, let's do it!"

Extra time - models of Mandela

:: Sidney Poitier (1997) - Poitier was nominated for an Emmy for his performance opposite Michael Caine as Mandela in TV film Mandela And De Klerk.

:: Morgan Freeman (2009) - The Oscar-nominated actor portrayed Mandela in Clint Eastwood's sports biopic Invictus about the 1995 Rugby World Cup after the dismantling of apartheid.

:: David Harewood (2010) - The Homeland star portrayed Mandela in TV drama Mrs Mandela, with Sophie Okonedo as Winnie.

:: Terrence Howard (2011) - Howard played a young version of the late statesman in Winnie Mandela, which starred Jennifer Hudson in the title role.

:: Mandela: Long Walk To Freedom opens in cinemas on Friday, January 3 2014