This invitation to lecture to the Swindon Branch of the Society coincided with a period of crisis and change in the air transport industry where events stemming from growth, new technology, commercial challenge and political action were bringing about unprecedented ferment. Admittedly it could be said that the manufacturing industry has known this condition continuously for 20 years. But whereas the manufacturing industry has run into problems arising from retrenchment in military procurement, there is no sign that commercial air transport will do other in the long term than continue to expand. The main question is, what is the most beneficial nature of the expansion? A correct analysis of the present situation is important to the transport industry and also to the design and manufacturing organisations that are interested in building aircraft to meet the needs of the expansion ahead.