The Army Navy had a Greener type safety lever. It had an engraved action, a full length (soldered) rib, and sporter stock and sights. It had seen a LOT of service. I don't recall the Captain's last name but it looks like he served in Egypt and may have lost his life there. Someone, perhaps the guy that shot him, applied some metal icons to the stock that were definitely not of English origin. If someone wanted to line it they could, but I don't trust liners in centerfire calibers, as the liner has to be fatter than the ctg case and that entails removing a LOT of metal from the barrel and soldering in a liner that has thin walls and is a sliding fit in the bored out barrel. All it needed was a 3 lobe tumbler, and I foolishly assumed that there was only one variant on that theme, having only the Greener action to go by.
Army Navy didn't make guns, they only retailed them. So the real maker of that rifle is unknown, even though the Univ of Glasgow has all the AN records.
I have never seen one with a sliding safety.
The 400 NE is a "nitro for black" ctg with a working pressure of 14 tons. That's pretty mild so I don't have any qualms about it. In any case I plan to use it to shoot 410 shotshells made from 9.3x74R brass through a fully rifled slow twist barrel, allowing me to shoot "slugs" (cast bullets using 38-40 load data) as well as single stack 000 buck using 410 shotgun data. More correctly, it should be called a 10x74R even though the chamber is identical to the 400 NE, the bore is a bit tighter at .401" vs the standard .405". I am trying to get the 000 buck to group tightly so I can extend the range to 100 for hogs and coyotes. I have done some experimentation using a 41 mag and the rifling definitely tightens up the grouping. Not too different from shooting a muzzle loader with multi ball, but using a plastic 410 wad instead of patches.