It is naturally a great privilege to have been asked to give the 20th Henson and Stringfellow Memorial Lecture here at the Yeovil branch, within a few miles of the place where Henson and Stringfellow worked together and performed some of their historic experiments.

It is perhaps equally natural that, Yeovil having become the home of rotary wing VTOL in the UK and my own Company having pioneered high speed wing VTOL that I should have been asked to make some aspect of VTOL the subject of my paper.