In South Africa, celebrations are to be held to mark 20 years since the release from prison of Nelson Mandela, a key step towards ending apartheid. In Cape Town, his former wife Winnie will lead a march from the prison where he spent the final months of his 27-year imprisonment. Mr Mandela, now a frail 91 years old, is expected to make a rare public appearance this evening. He became the country's first black president in 1994. He was sentenced to life imprisonment in 1964 for plotting to overthrow the government by violence.