Bren gun Markings

I've got a de milled Bren. It has been cut through the receiver and the barrel has been cut twice. It has been re welded but obviously missing all internals of the action. Suprisingly many features still work safety/fire selector, adjustable sight (out to 2000m), mag installs (mag has some kind of dummy round, butt stamped 1942 dag v11). The rifle itself has multiple markings Including

Dp 1187 next to rear sight
JI on the mag well cover
Dp is stamped into the steel in multiple places and carved in to the wood on the grip, butt stock and carry handle
Inglis (which I have found to be the Canadian manufacturer
Dp17 opposite the barrel release lever
Bren M....the rest is missing due to re welding.

I tried looking up this information but have yet to find any meaning to these marks. If anyone knows anything about these markings I'd be very curious to learn the history of this great piece of history

 

The "DP" markings stand for "Drill Purpose"
http://www.thegunner.net/brenrecg.htm