Frank Chikane served in the South African presidential office from the time of Nelson Mandela to Jacob Zuma - so he was privy to what went on behind the scenes. Now he has written a book in which he describes for the first time his account of Thabo Mbeki's removal as South Africa's president. He says it was a painful and humiliating episode for Mr Mbeki and it exposed the deep rivalry at the heart of the ruling African National Congress which continues to divide it today.Zeinab Badawi asks if the ANC become so riven with factionalism and corruption that it can no longer govern effectively.