I'm no expert on the field, but the key word difference here is innovated not invented whilst you're right in thinking the British industrial revolution laid the foundations for an eight hour day, I do believe that Ford and many like him really were the ones to put this idea into practice. (e.g. like how both Marx & Engels two Germans coined "Communism" in 1848 yet it was really put until Russia's 1917 revolution)

There are several sources to suggest that the idea of an 8 hour day originated in the UK: Chase. E (1993) & Bachin. R (2016)'s piece for the Illinois Labour History Society. Yet those like Teddy Roosevelt & Henry Ford really ran with the idea (e.g. "Ford gives $10,000,000 To 26,000 Employees" - New York Times, 5th January 1914). You should also remember that Ford was the one that created the assembly line reducing the need to work longer hours.

That's as comfortable as I'll get discussing this without delving into speculation but (without putting them on the spot) I'd suggest talking to /u/henry_fords_ghost, /u/Cosmic_Charlie & /u/agentdcf