"I can't help it if the ladies take note of me," Nelson Mandela once said. "I am not going to protest."

The thrice-married former president of South Africa is a celebrated charmer who, even in old age, has captivated celebrities such as Naomi Campbell and the Spice Girls. But one woman, it has been claimed, turned down a proposal of marriage from Mandela before he went on to wed his current wife, Graça Machel.

Amina Cachalia, a distinguished activist in the anti-apartheid struggle, politely rebuffed the great statesman in the 1990s, according to her son, Ghaleb.

"She called me and my sister aside and said she wanted to tell us about this proposal and that she was not going to accept it," Ghaleb said on Monday. "She was very matter of fact about it."...