Drawings by Nelson Mandela of his prison cell on Robben Island and the village of Qunu, where he was born and laid to rest, will go on public display for the first time this week at an exhibition in London. Mandela produced the drawings, using charcoal and pastels, in the years after he stepped down as president.The collection of original artworks remained hidden away for a decade but will now go on sale.The value of the 24 works is not known but is believed to be "substantial" and will be sold only as a single lot to a buyer who will guarantee they will remain available for public view.Mandela signed a commercial tie-up with the Belgravia Gallery in London, which also represents Prince Charles, in 2002 and began sketching in the dining room of his home in Johannesburg.The sale of the works follows his death at the age of 95 in 2013. Money raised from the sale will go to his family and to charity."I think they are historically really interesting works of art," said Anna Hunter, the gallery's owner, who negotiated the deal to sell his art at a meeting with the former president at his home."These are the drawings of a man who has been through so much and yet is willing to return to the subject matter."This is his triumph over the adversity he experienced," Hunter said. "He said to us that 'when they finally let me retire I want to be a full-time artist'. He might have been joking but he really enjoyed sitting at his dining table and drawing. It was a real escape for him."Hunter said the works were genuine, had been fully authenticated and were backed by Mandela's family.She said Mandela's eldest surviving child, Makaziwe, would attend the official opening later this week.Mandela is not well known for his drawings but they come with controversy attached.A limited series of lithographs produced by Mandela, in collaboration with an artist, depicting Robben Island and his cell, were sold, many of them to international celebrities, with proceeds going to his charities for homeless children and Aids victims.It was reported at the time that artwork purportedly by Mandela was being produced and sold with faked signatures. In 2005 Mandela filed a lawsuit against a former lawyer for allegedly selling fake artworks bearing his name. ..