Naomie Harris says Nelson Mandela's ex-wife gave her a carte blanche to 'play me as you see fit' in the film Long Walk to Freedom.
Speaking to TV Africa Correspondent Rohit Kachroo at the film's premiere in Johannesburg, Harris said she found the conversation with Winnie Mandela "liberating".
Idris Elba joined Winnie Mandela, the ex-wife of former South African president Nelson Mandela, and her daughter Zindzi Mandela, at the premiere of Long Walk to Freedom in Johannesberg.
Elba plays Nelson Mandela in the film which is expected to be released in the UK on January 3.
Nelson Mandela's daughter Zindzi said the new film about the former South African leader's life "forced her to confront many emotions" she had buried.
The trailer for the new Nelson Mandela film Long Walk to Freedom, which has its premiere in South Africa later today.
British actress Naomie Harris, who plays Nelson Mandela's wife Winnie in the new film about the former South African leader, said she and compatriot Idris Elba spoke in their South African accents "all the time" after filming started.
British actor Idris Elba had to be taken off a South Africa-bound plane and was rushed to hospital after suffering an asthma attack while on his way to Johannesburg to promote his new film A Long Walk to Freedom.
Elba, 41, missed a news conference in Johannesburg today to promote the film Mandela: A Long Walk to Freedom after being taken to hospital in the UK. But the film's producer Anant Singh said he was expected to appear at a planned red carpet event on Sunday.