For more than two decades the ANC has been South Africa's impregnable political structure, but now cracks are appearing. At least 30 ANC MPs defied the party whip and supported a no confidence motion against party leader and national President, Jacob Zuma. Stephen Sackur speaks to Pravin Gordhan, the man President Zuma sacked as Finance Minister in controversial circumstances earlier this year. Does the ANC need to be broken up to enable South Africa to thrive?