Some great points made, some that I have mused over myself before posting. The question regarding the bolts lead me to look up the history of hex drive (Allen) bolts, as although I knew that they have been around a long time I didn't know just how long. Well surprisingly, William Allen patented in 1910 the process for cold forming a hex head on a screw with manufacturing starting soon after. I would need to cut down (not enough clearance) some imperial Allen keys to check that they are indeed pre-metric! On the point that they would never have commercially produced a grip design with two bolts at the rear and a pin at the front, we will never know. It could have just been made to give an overall impression of what a slant-gripped pistol could look like. With the grips on, the join at the rear of the frame is virtually invisible, and the keyed-in front trigger guard is a very close tolerance fit. As a showpiece, this is all that would have mattered. A new single piece lower trigger/grip frame is also a stronger design than just trying to add a slant grip frame to an existing full trigger guard of a Mk1. Why an aluminium grip rather than a wood grip could they have been thinking of going down the route of cast aluminium for production?. I keep thinking of the four coincidences that took place on this pistol if it was a home engineered project. The late serial number, no other markings (and no evidence of any having been removed), a skilfully machined and fitted part, and a uniform patination across the two parts suggesting steel of the same age and stock. I would love to know for sure one way or the other but this may well never happen!