The only countries to which this particular build style is extant is in North America and the UK, though the patterns are more stylistically varied in the UK than they are here. It's not clear to me if they were a case of Americans continuing to produce variations based off of English tool lineage or if it was an American invention that was then adopted and "naturalized" back in the UK later on, as was the case with American scythe snaths. They date back to at least the early 1800's and the eyes were forge-welded rather than electrically welded. They were not cast, and you are likely thinking of the term "cast steel" which was used to describe cutlery-grade steel produced via the crucible method, and was the highest grade steel production method of its time.
I'm actually working on a short demo video on proper technique right now. I've seen a lot of videos on the 'tube involving bush hooks, but have yet to encounter a single one that shows them being used properly.