Thanks for the help Evert and Trajectory. There are so many different variations that it will be a case of buying one when it turns up. The quarter stock version really does interest me though I had no idea that they were made in different places and over a long stretch of time.
I will dig the 46 out but I think its beyond my meagre skills... it really was used to prop a door open! (thats how I came across it many years ago now). Probably for somone with a deep love of Diana Milbro to have a go at.
Thanks again for the help- my list of rifles to obtain is getting longer.