Just a guess, but is it Louison Bobet? Help me out, mes amis -- I know that Bobet bikes were rebadged Merciers, and that he had a continuing relationship with the Mercier company. Unfortunately, the figure on the eBay bike's seat tube decal is too cartoonish to make a positive ID. FYI, this is the fourth seat tube decal variant I've seen, other than the one I've describe on this list in January and the two shown on CR's Mercier page -- all within the span of a decade or so!
Ian Kersey