GregAlex, In the 50's and 60's I used to work for my dad min his electronics company. Through this I was involved in quite a batch of different sports in the Netherlands, and ballooning was one of them. One person in particular I remember very well. His name was Jan Boesman and besides being a balloonist he was also an ardent philatelist. He would always carry mail on his "flights" and some of these can still be found on E-Bay, Bidstart and Delcampe. One sale on E-Bay that ended is #
390966537126.
Peter