Mandela's widow: World struggling to find 'ethical leadership' Nelson Mandela's widow and women’s rights activist Graca Machel says one of the biggest challenges facing the world today is finding "the kind of ethical leadership which characterised Madiba's generation", saying that "millions of citizens are yearning for leadership with integrity". Members of Nelson Mandela's group The Elders including the group's Chair Kofi Annan and former UN Secretary General Ban Ki-Moon are in London as part of the new global ‘Walk Together’ initiative in Mandela’s memory. IMAGES AND SOUNDBITES