Frank Barnwell was a man who combined vision with practical achievement and as such earned tremendous respect. I am sure he would have enjoyed the challenge, as well as the vision, of further shrinking Everyman's World by making Supersonic Transport a commercial reality.

I am indeed honoured in being asked to give this 1968 lecture in his memory.

Right at the start I would like to pay tribute to all of my colleagues who have done a great deal of work preparing the material for this paper, and to say that without their help it would not have been an interesting paper at all.