Perhaps clarification of the question is in order. The question as written "What do most people consider the golden era of SxS guns from the high end English makers." My interpretation of the question is not when was the hayday of the sxs rather, I take it to mean when did the English sxs reach it's pinnacle of manufacture from a quality standpoint including workmanship, grace and handleing as well as over all beauty. If this be the case, then the late flint period (1810-1825). However, if the question refers to when the sxs reached it's heyday, then I would suspect the period to be somewhat later, sometime after 1870.