I'm afraid we've been no help at all. While not knowing specifically where you're at in your double gun experience, whether you were more in need of an instructive book on the double gun and its maintenance, perhaps including the shooting of these guns, or more an enjoyable read about a certain facet of the history of these guns we've fired a barrage of book titles filled with all things double gun, from soup to nuts.
Then to confuse matters, you later give a vague indication of working intimately with British double guns in your daily employment.
Perhaps you could help us help you by indicating which aspect of double guns you would enjoy reading most, whether a history of a specific make of gun, or perhaps a primer on the shooting of double guns or something on an altogether different double gun path. I think you get my drift on this. While not wanting to "go in blind and end up asking for something that might be too simplistic" you've gotten a ton of suggestions which you say you "will search for them and see which will be the most interesting", which if you DO you will surely end up blind.
Again, just a hint of what you'd like to read will get you a collection of titles that will both serve that purpose andn be easily tracked down.
