Margaret Thatcher refused to impose economic blocks despite intense pressure and branded Mandela's African National Congress (ANC) "terrorists". Less than a year after becoming Tory leader, David Cameron denounced the approach the Conservatives had taken in the 1980s.
Lord Tebbit said: "I'm not sure that it was thought that it was our business to instruct South Africa how to manage its internal affairs but we did not think that seeking to damage the South African economy would contribute to the search for a perfect settlement and we were proved right.
"It might have ended it (apartheid) earlier but it would probably have ended it in violence and bitterness and history shows that that was not the way it ended."
Asked how much credit he gave Mandela for that, he replied: "At the end I gave him enormous credit for it. He was able to come out of prison after 27 years not bitter, not angry and able to look at the world and change his mind on a number of major issues and I think that is a tribute to him."
Lord Tebbit, who claimed in the 1980s there was a "stinking hypocrisy poured out dail" about South Africa, was asked if he regretted comments he made at the time. "We all sometimes say things rather heatedly that possibly, in retrospect, might have been said more calmly."
Lord Tebbit dismissed suggestions that he should have regrets about how his government dealt with South Africa. "You have to act within the constraints of the time and I get very irritated by people who judge the past by the present. It is not very sensible," he said.
Reminded that many Tories had called Mandela a terrorist in the 1980s, he replied: "He was the leader of a political movement which had begun to resort to terrorism."
Mr Cameron admitted that Baroness Thatcher had been wrong to brand the ANC "terrorists".
He flew to South Africa in 2006 and told Mandela: "The mistakes my party made in the past with respect to relations with the ANC and sanctions on South Africa make it all the more important to listen now.
"The fact that there is so much to celebrate in the new South Africa is not in spite of Mandela and the ANC, it is because of them - and we Conservatives should say so clearly today."