I believe G&R Dewhurst may have been cotton merchants. Not a makers ID so it could just have easily been added at any time in the past. . The OP is right there are a lot of good copies out there so identification from photos is always fraught with danger. You can generally identify the style of the furniture but you need a close up view of the patina, joins, underside, construction method, what glues have been used (and for that age it should be an animal glue), type of screws, dowels or nails, the type of timber used etc.