I felt very honoured when asked to give this lecture in memory of one of the leading figures of the period which saw the greatest British achievements in aeronautics. The contrast between the technical situation of those times, and the uncertainties of today, immediately sprang to mind, especially in regard to British achievement (or lack of it) in space.So also, very naturally, did those occasions in the 1940's when I used to visit Mr. Chadwick to discuss the propeller problems of various Avro aircraft, both real and projected. During the course of these sessions, we often discussed future propulsion trends, including the relative merits of piston and turbine engines, propellers and jet propulsion, and so forth. I cannot honestly recall that the question of space flight ever came up, although it probably did, because propulsion is even more of a fundamental problem for flight in space than it is within the atmosphere, and even in those days I was what the Americans call “a space cadet.”