When delivering a Memorial lecture it is customary to open with a tribute to the one who is remembered. But the substance of my lecture is the rotor which Cierva evolved 50 years ago and I hope to sufficiently recognise his contribution during the delivery. Therefore with your permission I will content myself now with marking my deep appreciation of the honour done me by your invitation.

An informed layman reading past papers on rotors and rotorcraft would form the impression that each achievement was only a fleeting gain. The autogyro was to give way to the helicopter, the helicopter to the compound helicopter and the compound to the convertible rotorcraft. The rotor itself, it was argued, is ideal for hovering but hopelessly inefficient in forward flight. Hence the haste to get back to wings, a tendency much increased when fixed wing designers discovered how to use small, heavily loaded, rotors. But such is the lure of the rotor that even its detractors saw the case for its use in landing and take-off.