Timex established a complete manufacturing facility in Dundee, Scotland during the mid to late 40's. Dundee is about 50 miles from Edinburgh on the banks of the River Tay. Bill D. has far more information at his fingertips than I do, but the plant produced almost all the models current at the time, although there appear to be slight regional/time variations - such as production of certain models started AFTER they were in production elsewhere.
The plant eventually went on to produce the Sinclair/Timex ZX computers under licence, alongside continued watches, and a number of innovative other (non horological) products were made in limited numbers, until a very acrimonious union and management dispute resulted in the eventual closure of the factory. The majority if not all, parts were produced or sourced within the UK for the wtach ranges, however we do know that dials, cases, complete movements, parts for movements and etc., were shipped around worldwide as required.
Add to that - interchangeability - a caseback marked GB may even have been swapped out by a watchmaker or enthusiast like ourselves, and so it's not really possible to use country of origin as set in tablets of stone. Always check out any inked on markings inside the caseback and never clean 'em off, they MAY at sometime in the future, be able to be crossreferenced to one or other of the production charts/manuals that surface every now and then.
Frae Edinburgh, Bonnie Scotland
Affordable and Everyday Watches
My other hobby - Sequence Dancing