Mandela: Long Walk to Freedom failed because Steve McQueen's Oscar-winning film, 12 Years a Slave, "sucked up all the guilt about black people that was available," according to its director, William Nicholson.

Nicholson made his comments at a recent talk during the Hay festival, as he explored the relative failure of his biopic on the South African leader.

Nicholson told the audience that his subject’s death on December 5 last - immediately before the film's release - had hampered its success. He also claimed to have invented many of Mandela's speeches in the film because the former South African President's speeches were "boring".

Long Walk to Freedom, based on Mandela's autobiography acquired one nomination only, for Best Original Song at this year's Academy Awards, following less than enthusiastic reviews.

By contrast, Steve McQueen's film, 12 Years a Slave, starring Michael Fassbender, won Best Film, Best Adapted Screenplay and Best Supporting Actress. The film also received nominations in six other categories. Plus the critics loved 12 Years a Slave, almost universally, making it a sure-fire box office hit.