There is of course, another statue of Mandela in Parliament Square, and your author was lucky enough to be present in August 2007 when Mandela came to London to speak at the unveiling his statue in Parliament Square. He told a story about how he and his friend Oliver Tambo visited Parliament Square and Westminster Abbey in 1962, joking that one day a statue of a black person might be erected in Parliament Square alongside former South African leader General Jan Smuts. That dream came true and Mandela's story is a demonstration of how humans can change the world for the better. He will be missed.
For more on the Southbank statue, see http://www.london-se1.co.uk/news/view/2573