WTK - history on a little VP pistol

Have an intersting little FN Baby 6.35mm (.25 auto) pistol. On the left side of the slide the pistol is marked Fabrique Nationale D'Armes De Guerre Herstal Belgique & Browning's patent Depose, on the right side of the slide there are 3 proof marks on the slide under the ejection port and matching proof marks on the frame. Grips are simply marked FN (in a circle), and "Baby". Serial number is 18XXXX. The pistol retains around 70 - 75% of the original blued finish and has black (rubber?) grips. It does have both a trigger, and magazine safety (pistol will not fire without a magazine inserted).

I believe this is a European market Baby Browning. I have seen a ton of baby Brownings, and their 8 billion clones - what I do not know is how rare are these in the US (again - considering that this is an FN [not Browning] marked pistol)?

Any ideas how old this little pistol is? According to Browning's records, the SN# range would put it having been made in 1959 - BUT - since this is an FN marked pistol - do Browning records apply to this pistol?

I have no intention of selling this little pistol but was curious if anyone had any additional information on it.

Thanks