Naidoo spent a year in solitary confinement rather than testify against her friend Winnie Mandela and other anti-apartheid activists. Her defiance helped bring about the collapse of the apartheid state's Trial of 22.

On a winter Friday in 1969, the security police walked into a bedroom in Johannesburg and told Shanthivathie Naidoo to pack a bag. She was dressing for another ordinary day at Vanguard Books, the small shop off Market Street that had become a meeting place for the city's dissident writers and trade unionists.

Her mother stood watching. "Pack your bags," the men said, "we are detaining you under the Terrorism Act." Naidoo was given no reason and no warning. She would not sleep in her own bed again for 371 days.

Shanthivathie "Shanthie" Naidoo, who has died at the age of 91, spent a year in solitary confinement rather than testify against her friend Winnie Mandela and other anti-apartheid activists. After five days of interrogation without sleep, during which she was forced to stand until she hallucinated, she was sentenced to prison for refusing, in open court, to betray her friends.

Her defiance helped bring about the collapse of the apartheid state's Trial of 22, in which Winnie Mandela and 21 others stood accused of furthering the aims of the banned ANC, and made her name known in newspapers from Johannesburg to London. She herself resisted the word "activist", preferring...