He is due to attend an outdoor concert in his honor in Hyde Park on Friday. Performers include Queen, Annie Lennox, Leona Lewis and the Soweto Gospel Choir. Troubled diva Amy Winehouse is also scheduled to sing, if her doctors allow it. She was taken to a hospital last week after fainting at home.
Proceeds from the concert will go to the 46664 charity, the AIDS charity named for the number Mandela wore while imprisoned by South Africa's apartheid authorities.
Mandela also is due to meet prominent supporters, including Prime Minister Gordon Brown, former U.S. President Bill Clinton and talk show host Oprah Winfrey.
Mandela, who turns 90 on July 18, has visited London many times, and has expressed gratitude to the city for the constant vigil that was held outside the South African Embassy during the apartheid years.
Friday's concert coincides with the 20th anniversary of London's Free Mandela concert, held to demand he be freed from prison.
He was released in 1990 after 27 years behind bars, and was elected South Africa's first black president in 1994.
