What a beautiful rifle. A superb double showing very nice lines and excellent build quality!
The chambering of course is for one of the best all round cartridges ever created. The 450-400 NE 3".
The very first double rifles that I ever shot were 450-400 NE Jeffery boxlocks.
I well remember a day at the range back in the very early 1980's, where I was lucky enough to do some shooting with three different Jeffery boxlock 450-400 NE doubles.
About 10 years later I had a few shots with a Jeffery sidelock, again in 450-400 NE.
Nice rifles all of them, and I'll never forget those times.

Mark, thanks so much for showing us the build and completion of this lovely rifle. You obviously really know your stuff.