Nelson Mandela is no stranger to London. The city loves the South African statesman and Friday night nearly 50,000 gathered in London's Hyde Park to celebrate his 90th birthday. From the British capital, Tom Rivers reports.

Nelson Mandela, left, waves from the stage, as US actor Will Smith smiles from behind, at the 46664 charity concert in honor of Mandela's 90th birthday in London, 27 June 2008

Back in 1988, this reporter remembers this song being sung at a concert held in Nelson Mandela's honor at the old Wembley stadium. Back then Nelson Mandela was still a prisoner of the apartheid regime.

The tone of that concert was one of frustration. This concert by contrast was one of celebration. And amid the various musical acts, Mandela himself took to the stage.

"Twenty years ago, London hosted an historic concert which called for our freedom," he recalled. "Your voices carried across the water to inspire us in our prison cells far away. Tonight, we can stand before you free. We are honored to be back in London for this wonderful occasion, celebration. But even as we celebrate let us remind ourselves that our work is far from complete."

The man who would eventually be released from prison in 1990 and be elected the first black president of South Africa four years later was referring to his campaign these days of preventing the spread of AIDS.

"After nearly 90 years of life, it is time for new hands to lift the burdens. It is in your hands now. I thank you," he said.

His birthday is actually not until next month, but the logistics of the London concert meant that it made more sense to hold it a couple of weeks early. And to a man who has seen so much in his long life, the thousands in Hyde Park raised their voices.

The star-studded event featured the likes of Amy Winehouse, Eddy Grant and Johnny Clegg.

Organizers vow that the work of Mandela's AIDS charity will go on.