Adelaide Tambo, wife of the late Oliver Tambo and South African former President Nelson Mandela attend the unveiling of the O.R Tambo International Airport 27 Ocr 2006 in Johannesburg

Adelaide Tambo collapsed in her home late Wednesday, and died soon afterwards from an apparent heart attack. Her death, at 77-years, was unexpected. Earlier in the day, she had visited her doctor for a checkup, and was pronounced fit and healthy.

Mama Adelaide, as she was fondly known by many South Africans, was harshly exposed to the reality of apartheid as a 10-year-old, when her octogenarian grandfather was flogged by white police in the town square in Vereeniging, an industrial town south of Johannesburg.

The young girl cradled her unconscious grandfather in her arms until he revived, and later said the incident sparked a life-long determination to fight racism and apartheid. By the age of 16, she was acting as a courier for the African National Congress, and became a branch leader at 18.

In 1960, following a major crackdown on the liberation movements by the apartheid state, the ANC instructed her husband, Oliver, to leave South Africa and set up an external wing of the organization. Adelaide followed a few months later, and the couple settled in London.

Their home became a refuge for hundreds of South African exiles over the years, including former President Nelson Mandela, before he was jailed, and current President Thabo Mbeki. It was there that Tambo, working as a nurse to support her family and many others, became known as Mama Adelaide.

Thembi Modise, former ANC soldier and current speaker of the North West Province parliament, told national radio, Mama Adelaide's caring embrace accommodated any who needed it.

"But I think all of us will always remember Ma Tambo for loving everybody," said Modise. "For loving the poor, for opening up her arms, for making sure that people had food. Because she believed that you would never think, if your stomach was empty. She went all out and fed all of us."

Modise says that, during that time, Tambo took a special interest in the women soldiers of the ANC's military wing, sending care packages that included new underwear and the occasional bottle of perfume to their camps in remote African locations. She knew, said Modise, that the women greatly valued the little things that reminded them of their femininity.

The Tambos returned to South Africa in 1990, but Oliver Tambo died of a stroke in 1993, and never saw the democracy for which he fought so hard. Mama Adelaide served a five-year term in the first democratic parliament, and since 1999, busied herself with charities that care for the elderly.

Speaking on national radio, former parliament speaker Frene Ginwala reminded the country Tambo was one of a special generation that is gradually passing from the South African political and social landscape.

"We are losing the values, the principles, the love of that generation. We are losing a parent, as a nation," said Ginwala. "One of the tragedies of current South Africa is that they did not have an opportunity to really know people like Adelaide or Oliver Tambo."

Tributes have been pouring in from across the country. Elder statesman Nelson Mandela said Adelaide Tambo was an exceptional woman, who dedicated her life to freedom and service. President Thabo Mbeki said she devoted her life to the struggle against apartheid and against sexism.