Don't confuse available technology and choice of mechanism with the quality of the product.
Whether it has a flat back to the action (which early Westley Richards A&D guns of very best quality did) or a half-moon, scroll, concave or other fancy back was a stylistic choice based on prevailing trends. Nothing to do with quality.
What you or I now decide we like is not an objective criteria by which to judge a gun. You need to look at the care and quality built into it.
Hi Dig and thanks again! You hit the nail on the head again. Look at SL guns, while it's common belief that a Best gun must be stocked to the fences, early Best guns were not, just that fashion changed. I have a Henry Atkin with a makers letter stating that the gun was a Best grade gun, yet it's not stocked to the fences as an example.
When I first wrote this post it was one to get a discussion going and see what thoughts others have on this subject. It's been interesting.
I think most of us here can tell a quality gun from lower quality ones, just a matter of having the gun in hand and some other features.
As been said, fit,finish, engraving, wood all play a part in determining grades. But........like everything else in the trade, there are no absolutes! Brit guns are a fun journey with plenty of twists and turns.
Thanks again all!
Greg