Contributor(s): Professor Paul Collier | The natural assets of the poorest countries constitute the biggest single opportunity for transformative development. Paul Collier is a professor of economics at Oxford University and co-director of the International Growth Centre. The author of The Bottom Billion, which won the 2008 Lionel Gelber Prize for the world's best book on international affairs, he has lectured widely on the subjects of economics and international relations. He was the senior advisor to Tony Blair's Commission on Africa, and was Director of the Development Research group at the World Bank for five years.