Hermione Cockburn tells the story of the man who added lead to petrol and later put CFCs into fridges. Both were great advances in their day but ultimately came with great environmental costs. Midgley became an honoured scientist because of these two discoveries, but the legacy of lead pollution and CFC damage to the ozone layer have overshadowed his work. A stark reminder that we cannot foresee all the consequences of scientific and technological advance. Producer Mike Hally