The advent of mechanical power which could be generated at will by the combustion of cheap fossil fuels made the windmill uneconomic and few now remain in the United Kingdom. Nowadays, fossil fuel is no longer cheap and the economics of wind power are once again beginning to look atractive. The article discusses various aspects of the subject and the possible applications in the United Kingdom, including horizontal axis machines, power availability, windmill design, vertical axis machines, lift type machines, ducted rotors and augmented systems, and the economics of wind power.