Stephen Sackur talks to Mamphela Ramphele, anti-apartheid activist, prominent public figure and former partner of the late Steve Biko, one of the heroes of the liberation struggle. She has launched a new political movement with an outspoken attack on the failings of ANC governance. The political supremacy of the African National Congress in post-apartheid South Africa has never been seriously threatened. She says she is on a journey to realise South Africa's dreams, but how far will she get?