I found him a tricky person to deal with, felt like I was walking on eggshells most of the time. I did manage to get my car after a fashion.
Interestingly I've recently been contacted through this site by the person who has (or had) the original green log book for my Isetta, so if it's still in existence I may finally be able to trace at least some of the history of the car prior to 1983.