Monsieur Griffe was a clothing designer, who worked his way up from the bottom to success as a fashion designer. I can find no reference to his ever being a perfumer, so I would suspect the actual work on Grilou was done by a fragrance house under his supervision. Your find is a very interesting one and I, for one, would like to know what further you find about Grilou's history. If possible try to give us an idea of what the fragrance is like. We have some French speaking members, so perhaps a translation might be helpful.
Here is a web address for the Perfumed Court where I found another fragrance by Griffe which they tout as very rare. Note how pricey it is for 1ml.