Artistamps Perhaps?

This is a new one to me - I'm familiar with the Trutial State (Dunes) that have a mass of postage stamps from a legal source - but these stamps that I ran across seem to have a basis from fictitious countries - and the name Bruce Grenville comes up - and the phrase Artistamps which may be a legitimate art form. Anyway, can anyone shed any more light on these - I assume they fall in the category of Cinderellas.

This article might interest you on the subject (see page 5 for information on the stamps scanned above):

http://www.stampnewsonline.net/Stam..._Occussi.pdf

Thanks wt1 - you are a resource extraordinaire!