Phumzile Mlambo-Ngcuka stands at the centre of two of South Africa’s current preoccupations: the drive for faster economic growth, and the noisy debate about the presidential succession.

President Thabo Mbeki named the 50-year-old Durban native as his deputy last year after sacking Jacob Zuma, who faces trial on two counts of corruption. As the first woman to take the post, her honeymoon was short: Conspiracy theorists immediately seized on the fact that she is married to Bulelani Ngcuka who, in a former job as head of public prosecutions, first said Mr Zuma had a case to answer.