Sorry David, I can’t give you a definitive answer concerning its origin. At first I thought it might be Spanish. Spanish locks tend to show a strong Gothic influence (as seen in the archtectual features on the lock), and are not as intricate and ornate as their French and Italian counterparts. And, of course, we both know that the Spanish Hapsburgs once ruled Belgium. However, even if there is some Spanish stylistic influence, I believe it was most likely made by a local locksmith from Belgium or the Netherlands. But, of course, this is more speculation on my part. Take it for what it’s worth.
