I did a little more checking. Your Halifax is the "model" of shotgun for Darne shotguns from France. Here is a site that will show you the series and other info on your gun.

http://www.doublegunshop.com/darne.htm

There are marks stamped under the barrel that equate to the series of the gun. The guys over on the Gournet site should be able to tell you the year it was produced based on its serial number in the Darne forum.