Rich, would an early English trade gun, 1740’s, have had a sitting Fox on the lock plate? I don’t know the dates they were used.
In For Trade and Treaty there are Northwest guns with the deep trigger guard with the sitting fox on the lock. These below have that combination: Northwest gun, deep trigger guard, fox stamp on the lock.
Willets 1789-1812
Barnett flintlock c. 1820
Barnet c. 1815
Barnet 1838
Barnett c. 1876
Wilson 1824
Wheeler 1814-1819
Chance 1840 some obliterated stamp
Tryon (American) NW gun 1843-1859 has a bird stamp
Belgian NW gun c. 1852 fox on lock
Belgian NW gun 1858 fox on lock
Bumford Type G 1750-1760: no fox; round faced English lock no bridle
Wilson fowler imported for gifts by Sir William Johnson 1765-1780, cast brass furniture has no fox on round-faced English lock
Willets chief grade fowler, cast brass guard, no fox on round faced English lock.
Other sources match. The fox and/or tombstone stamps go hand in hand with NW trade guns having the deep, surface-mounted, strap metal guard and it is not found elsewhere.
HOWEVER early NW guns by Wilson and by Grice in The Encyclopedia of the Fur Trade: Firearms of the Fur Trade have the strap metal guard but no fox stamp. These guns are dated 1750s-1770. So the fox stamp was not universal on early NW trade guns.