I must disagree. This gun is totally English in its styling, as well as all its components. It may well even be an imported rifle that Bartlett & Bros stamped their info on the barrel. The buttplate and trigger guard, with the pineapple finial are English, as is the breeching/lock combination which was a Rigby design. Most English sporting rifles have sling swivels and they are not uncommon, nor is the checkering on the wrist. Contrary to being an assembled gun, anyone who has built an English rifle knows the architecture is not easily attained. Likewise, these rifles were unadorned as the English style had moved to functionality by this time. Without knowing anything about B&B, it could be a later gun....perhaps in the 70's.
In the closeup of the rear sling swivel, there is a twig inclusion, extending in both directions, which has been filled. This same inclusion is evident in the buttplate picture showing the it extends clear around the stock. How the flaw was repaired could indicate if it is original to the gun, or filled with epoxy or other filler at a later date.
Superfluous additions in the description detract from the gun. If something is not known, it should not be added. This includes the "rarity" of the checkering and swivels, and the suggestion that it be rebored. Regardless, it is fairly priced.