When Nelson Mandela turned 60 while serving time on Robben Island, thousands of birthday cards were sent to him but he received only six. Yesterday his fellow Rivonia trialists Ahmed Kathrada and Andrew Mlangeni and his warder Christo Brand recalled their memories of birthdays on the island as South Africa prepares to commemorate Mandela's birthday tomorrow.Although, today, his birthday is celebrated in a frenzy of high-profile helpfulness, when Mandela was on Robben Island, July 18 was usually "just another day".Kathrada and Mlangeni said prisoners had always looked forward to treats, but Madiba had never wanted special treatment.Kathrada, who said he had waited years to buy something on the island for Mandela's birthday, said celebrations were rare."Every now and then we did manage to celebrate birthdays. Not only his, but [everybody's]. [But] it's not like we could just order biscuits and cakes. There were certain categories and only when you reached 'A' category could you buy things like coffee [from the prison shop]."It took me 13 years before I got to the 'A' level," Kathrada said.Fellow Robben Island prisoner, Andrew Mlangeni, said time on the island was never only about Mandela."It was nothing special. We celebrated everybody's birthday. We asked the authorities for permission to buy extra things such as biscuits," he said.Each year on July 18, South Africans are called on to spend 67 minutes helping someone less fortunate, as a dedication to Mandela's 67 years of activism.Mandela's prison warder, Brand, has fond memories of his birthday."On his 70th birthday I arranged for him to watch The Last Emperor. It was brought from overseas and wasn't released yet."It was brought by a delegation to Pollsmoor and we refused it, but his lawyers insisted we get the movie for him."Later that day we were drinking coffee and had rusks and watched the movie together," Brand said."On his 60th birthday, I censored the cards. He received thousands and thousands, and of all those only six, from his immediate family, [were given to him]."..