David was an experienced test pilot. During the 1970´s he was at BAC Weybridge. At that time I ran the ex TSR2 flight simulator and he was one of the pilots we called upon when investigating at the handling of project office aircraft. He still had contacts with Hawkers as I remember that he took time off to deliver a Hunter to Switzerland.
He managed to get help from the company for his private project- including flight test at Wisley and some wind tunnel work. I developed a simulator model from his drawings using the RAES data sheets. For a canard aircraft handling during the stall is very important - making sure that the foreplane never lost control.
There is a film on Youtube - search for Lockspeiser Aircraft - the Boxer. (Unfortunately the forum will no tlet me post URLS until I have made 10 posts.) You can hear David himself making the commentary.
He was a lovely man to be with.
Alan