I'm not sure if your omission is subliminal or deliberate, but one of the front-runners in the desire to make this a reality is Bremont. They have invested heavily in moving as much production as possible back to these shores and as far as I know (I have no particular affiliation with them) they are constantly investigating ways to "complete the circle" and create everything here.
I know they get bombarded with requests for "in-house movements" but as I recall the infrastructure costs if the tooling machines etc is enormous - but it's something they'd like to do I believe, although whether a single brand could achieve it, who knows.
Maybe a co-operative or collaboration would be possible?