I don't think it's Medici (tho they did use a Lion, this looks more like the Royal Stewart coat of arms) and I never saw a Medici with such lug-work (this looks a cut above typical Medici work!) but haven't seen everything they made, either. The folks at Cyclart keep meticulous records, they should be able to trace it for you...might not be free, however. There was a previous thread concerning an aero bike that had the AX rear brake mounted in such a fashion, but I can't recall what it was titled or whether that bike ever got positively ID'ed...sorry.
Truely a unique and Nice Bike, congrats!