Historically Parker always gets the nod for coming out with the first 28 gauge as their brain child, introduced in 1903, the first load was 5/8 oz of shot.......therefore American roots for the 28 gauge I would say......
Quote Jack O'Conner - The Shotgun Book - 1949:
"And the .410 is a direct decendant of the American 44-40. At first the standard 44/40 case was used, bottle neck and all, and the shot was in a paper container. Then 2-inch straight brass cases were used, then 2 inch paper cases, then 2 1/2 paper cases. At one time the shell was known as the .44 XL.......It was loaded with 3/8, then 1/2 ounce in 2 1/2 inch cases. Then in the early 30's Winchester-Western pioneered the 3" .410 shell with 3/4 ounce of shot and brought out the model 42 Winchester pump shotgun for it".......
End Quote......
Best,
