Greg, based on the photos, I'd say it is a best work gunOriginal Quality grade one (OQ1)). The locks 8 or 9 pin (depending on whether you count the tumbler or not), the engraving is over 75% coverage and looks like high quality, the wood is good (but may be a restock), and the fit and finish look up to best work standards. Some will argue that the flat back is not a best work gun. I'll concede that the later "London best gun" was stocked to the fences. However, IMO, many of the earlier flatbacks are best work guns, they simply were before a style change.
My guess is that you have a very fine gun. Atkin's built guns for smove real VIP's; Gough Thomas went there for his 'Optimum gun."
