The retired major-general with a mission to fight the corruption in Nigeria's public life works from an office in the back yard of a small poultry business in the sprawling outskirts of Lagos. Bearded, wearing a grey singlet and jeans, he cuts an unusual figure for a former top-brass officer. Ishola Williams heads the Nigerian branch of Transparency International, the anti-corruption lobbying organisation whose last ranking classed Nigeria as the world's second most corrupt nation, after Bangladesh. He sees in Nigeria a whole political system that has successfully resisted attempts to change its habits.