Hello Mark,
Thank you for sending in this pocket watch movement for an appraisal. Just one correction needed in your description. The name is not JD Jamison rather "Ja. Jamison' Maker to his Royal Highness the Duke of Kent. London"
THE WATCH MOVEMENT:
This is a brass plate, verge & fusee movement, signed on the back plate of the movement "Ja. Jamison' Maker to his Royal Highness the Duke of Kent. London". The key to the age of the movement lies in the balance bridge and the footing for the bridge. There is a monometallic broad balance wheel covered by a brass keyhole shaped balance cock or balance bridge which is jeweled to the center and has the index ruler pointing to a measuring scale on the very edge of the bridge where it toins the unengraved footplate. That layout points to the late years of the 18th and turn of the 19th century. The only listings of a James Jamieson (can be spelled multiple ways) working in London is found in Brian Loomes "Watch and clockmakers of the world, 21st century". There are two: J. Jameson working 1772-1796 and James Jamieson London working 1760. Therefore with that bit of information we are not dealing with a very well known watchmaker here such as George Jamison of London who has a long illustrious career.
Looking at the sides of this movement there are a lot of empty slots where gearing should be. This was most likely a verge or crown wheel movement but the contrate wheel is missing that is always associated with the crown wheel. It is also a chain driven fusee movement which the english continued to make well into the 19th century. The dial plate and rear plate are held together by baluster pillars of brass which does not help us with the date since the simple baluster pillar was the first and last type the english watchmakers used. Your rear plate is covered by a typical English dust cover which was first used back in the mid 18th century, so that is not an aid to dating the watch. There are no fancy brass decorations hanging from the rear plate and there is no evidence of complications such as repeater function or alarms. What is quite obvious is that there are many wheels missing from this movement, and that really hurts the value. The condition of this watch movement is rather poor.
COMPARABLES:
~https://www.ebay.com/itm/382450820970?hash=item590bd8676a%3Ag%3Afh4AAOSwRWVa6GNf&nma=true&si=mIsWeEDsvCCbbgOdCydyjibEBuA%253D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557ES (Sold on ebay for $203)
~https://www.ebay.com/itm/164721512753?hash=item265a2ad131:g:TuQAAOSwkiZgNiX~ (also sold for $203)
~https://www.ebay.com/itm/164721512753?hash=item265a2ad131:g:TuQAAOSwkiZgNiX~ (sold for $135.45 on Ebay)
https://www.liveauctioneers.com/item/44163639_four-english-gilt-brass-pocket-watch-movements-various
(four english movement sold for $271 in 2016)
Pricing:
The key to finding something of value has to be in more than just the name on the plate and a title. The piece has to be close to being original and genuine and no in need of milling brass gears to make the movement function. I see very little value here. The fair market value, as is, would be in the $50-$75 adn I do not thin a retailer would be interested, but the retail value is automatically answered by mearto as being twice the fair market value.