I get 1867 or 1827 for the case date letter. Neither seems right. The movement has a simple balance cock and exposed balance spring so 1827 is not sensible
1867 is very late for a pair case but that is consistent with the watch movement style.
Watch could be a lever or a cyliner or a duplex or even a detent chronometer (very unlikely) and we would need a good side view inside the movement to tell. Cylinder would be a lower grade but English made cylinders are unusual. Duplexes are desirable. I would expect this to be an English lever. A detent chronometer would raise this item to outstanding but they are usually on watches with better balances than this.
I apologize for using these terms of art but descriptions are on line so you can find them
It is a very clean watch and a nice, if very late pair case.
Whether it is "worth it" to have one is pretty personal question. It is a great example of silver smithing and may also be a pretty good watch movement. It has a solid gold balance which is less desirable than a truly functional bi-metallic balance but was consider more honest and relaible than fake bi-metallic balances which were common in the 1860's.
It seems to be in original clean condition which is nice.
It seems to have been a good quality solid watch in very nice cosmetic condition but except for the case not rare.
In my view every English case of this quality is a treasure.
It's not a fusee which would lead one to think the movement might even be early 20th century. Looks to me as though the date letter is 1907-08. But a PAIR care? But the solid rim balance is under-sprung which might imply it is much earlier. Mis-matched parts? I wonder if the movement is not original to the case? Hmmmmm!
I would go with a date of 1907, based on the shield that contains the "m". As late as this seems for a pair case, it is not impossible. I have a pair case with fusee in a Birmingham case hallmarked 1894. My movement is (other than the fusee) is the same as jjea's, including the undersprung solid balance, pinned plates and serial number format (mine is 8/3533). Mine, however, has a signature -- A.S. Sinclair with the town name Methlick. Methlick is in Scotland. I would guess this is just the sellers name. My case serial number matches my movement. As I understand, conservative tastes led to the production of pair case watches long after they were generally obsolete.
Also, I find that T.R.A. on jjea's case, could be Thomas Richard Arnott who was recorded as being active in the 1890s, at least.
Jerry may be right. The pair case kept me from accepting a 1907 date.my theory being that in 1867 casemekers were still alive who either made pair cases or apprenticed topeopel who had but by 1907 there was another generation. However English casemkers were artisans using very old tools and I suspect most could have made a pair case then.
I also thought the movement was too early for 1907. I applied the logic that even an outdated case would have a contemporary movement. I still think this is sensible but that is not always how things worked.
I think Jerry's assessment is more likely than mine based on the shape of the stamp which is pretty clear and the likley ID of the casemaker, who was very good.
latest English lever with going barrel and "double barrel" idler wheel,verry late IMHO 1890-WW I,maybe recased in an old case,if the Hallmarks indicate an earlier period.Nice and wearable watch anyway!The english cases were quiet standardized in size,so it´s easy to switch the mvmts.But often the winding holes don´t line up:Look for filled winding holes by breathing onto the back lid.The filled holes will apear then.HTH