The Mantons and their best apprentices raised the standards to which guns could be made by a very substantial percentage in the early 1800's. This happened in conjunction with a remarkable increase in wealth within the British Empire. Wealthy Brits became very focused on goods of extraordinary quality, guns being one of the classes of goods where a "best" quality could be made. Suits, shirts, gloves, hats, shoes, waterproofs, umbrellas, jewlery, wine/chocolates, carriages, etc. were offered by Brit craftspeople in "best" grades which were usually "bespoke" and made to fit and to order. Read "Nothing but the Best" by Thomas Girton (a short, imformative, and entertaining read!!) fora moreindepthunderstandingof this subject.
"Best" gun needs to be considered over time. Materials. designs, and craft techniques, as well as style, have evolved over time. Note that "best" quality can't be identified by brand. Brand can, however, tell you the probability that a gun of that brand is a "best". Boss SLE's are for sure "bests." Purdey SLE have a much higher probability of being "best" than does,say, Midland (there was a pair of Midlands that I bet were "best" at auction a few years ago). Consider Greener "G" guns and top end Westley Richards Drop Locks for "best" boxlocks.
You have to look at enough "best" guns to learn to recognize "best work" when you see it.
