There's also a picture of it in Seymour's (I had about 5 or 6 of the 20s). I also displayed it at a F.U.N. Convention and nobody from France knew where it was from. A few years later a French coin dealer had one on display as well... but still no ID (back then).

Any idea where it's from?

Here's my purple oval next to a bicolor "AS" (location unknown by me).