Art expert Hannah O'Leary first laughed when she saw a valuable Irma Stern painting - once auctioned to fund Nelson Mandela's legal defence in the 1950s - being used as a kitchen notice board in a London flat. "Well, I couldn't believe what I saw. I walked into a small flat to see one of the artist's distinctive Zanzibar portraits being used as a notice board," she said yesterday."There were letters and postcards tucked into its magnificent frame, and badges and Christmas decorations hanging off it. I think my first reaction was to laugh!"Thankfully it is in wonderful condition." The specialist in South African art at Bonham's auction house was at the flat to value Stern's painting - Arab in Black - on the request of the owner, whose parents bought it in South Africa before moving to the UK in the 1970s.The painting was donated by Betty Suzman, the sister-in-law of anti-apartheid activist Helen Suzman, to a charity auction to raise funds for Mandela and other ANC activists during the Treason Trial."We have placed the estimate at £700000-£1-million (R13.5-R19-million) but its true value will be decided at the auction on September 9," said O'Leary...