When Hilda Ndude is asked to recall the mood 20 years ago on the day she walked Nelson Mandela to freedom, she utters one word: "Wow."

With the snap of a camera Ndude's face became part of one of the most hopeful images of the 20th century. In it she can be seen standing behind Mandela and his wife Winnie in the afternoon sunshine as they punch the air and salute victory. Ndude's own expression is one of deep concentration on the task in hand.

"It was out of this world," she told the Observer last week. "I don't think I'll experience anything like that again in my lifetime. There was incredible optimism. We knew a new South Africa had been born."

Ndude was head of protocol responsible for ensuring that Mandela's first public appearance for 27 years went without a hitch. Now 54, she is still fiercely loyal to the man she, like much of the nation, calls "Dada". But she believes the bright dawn of that day has been eclipsed and Mandela's legacy squandered. She became so disillusioned with his party, the African National Congress (ANC), that she defected to its breakaway rival, the Congress of the People (Cope).

During the apartheid era, Ndude was an underground activist who served time in prison. She was a leading member of the United Democratic Front in Western Cape and dealt with the releases of struggle heroes Govan Mbeki and Walter Sisulu.

In December 1989 she was invited to meet Mandela at the warder's house he occupied in Victor Verster prison in Paarl, near Cape Town. "I was privileged," she said. "It was a wonderful meeting. Some people had been saying Mandela had sold out because he had a telephone in the house, but he showed us round and assured us there was no telephone. He sent me a Christmas card to thank me."

The following February, with the ban on the ANC lifted by President FW de Klerk, the world awaited Mandela's release. Ndude recalled: "When we were informed by the Boers on the Saturday that Mandela was going to be released the following morning, we had to run around and I became in charge. I was one of the leaders who went to the house on the morning. I gave him a briefing on what would happen. I walked him out of the door."

Then came an extraordinary surge of emotion as supporters and photographers strained for a first glimpse of Mandela: "It was something I could not imagine. People had walked from Stellenbosch, from Khayelitsha, from townships all over Cape Town. Some had been walking since 5am to be there. It was jubilation. They were crying and laughing. There were tears of joy and laughter. You couldn't stop the people."

Ndude walked behind Mandela as he savoured his first taste of liberty. "He was overwhelmed by joy at being free after 27 years. He was also very statesmanlike. There was no time to talk to him about it because there were so many people. My concentration was more on people and security and making sure everything was working smoothly. I remember a journalist asking 'Who's this tough cookie?' But we never worried about Mandela's safety. There was no thought of assassination."

The Mandelas and their entourage got into cars to travel to Cape Town where he would give a speech from city hall. "I was in the main car with Mandela: It was a convoy and people were trying to find out which car he was in. Fortunately, it had tinted windows so they couldn't tell. All those cars had dents that day."

Ndude travelled abroad with Mandela in the early 1990s and became a leading light in the ANC women's league and the ANC in Western Cape. But she lost faith in the governing party over time and made the "difficult" decision to join other rebels in Cope in 2008. She is now an MP and the party's national treasurer.

She feels, with evident regret, that the optimism of 20 years ago has dimmed. Asked about Mandela's legacy, she said: "With the ANC going off on a tangent in the manner it has done, that has been squandered. It has been lost and I don't think we'll be able to recover it. Mandela wanted one nation where blacks and whites see themselves as South Africans. I think we fell short. One area I would highlight is the Truth and Reconciliation Commission, which was cut short in its lifespan. Wounds were opened but never given time to heal."

But Ndude has lost none of her affection for Mandela, now 91, even though she has not seen him for years. "When new people come round, they want to know, 'Who are you, what are you phoning about, in connection with what?' I remember one time phoning him and somebody did that to me. Later I met him in person and I told him, 'You know, Dada, I was trying to get hold of you. Even the Berlin wall fell, and now there is a wall between us and you in your office.' He laughed because he really has a sense of humour.

"Then he phoned me in the morning to set up the appointment himself, saying I must come and see him in his office. He was president at this time. When I walked in his secretary said, 'You can't just come without making an appointment to see Dada.'

"I said, 'No, no, no, the appointment has been made by Dada himself.' She went in to tell Dada that I was here and Dada walked out to receive me from the reception and walked me to his office and we had lunch together. That's the kind of man he is.

"He's a parent, a father, a statesman. He has an aura around him. He's one of a kind. Sometimes I was afraid of being alone in a room with him because he's such a big presence."

But the woman seen in one of his­tory's milestone photographs admits that she does not have a copy of it on her wall. "People all over the world have photographs of themselves with Mandela, but I don't have a single one anywhere -- but I still have his Christmas card." - guardian.co.uk