Alfa-Proj vs Ralkem vs Bren history?

I was looking at Nichols' two books and I am not clear on the actual history of this. I know Alfa-Proj was newer brand, but the book says maybe it was called Bren before? But the name on them were often Ralkem, often referred to as Ralk. I can't find any info to figure out what was going on. If all goes well I have acquired my first Ralkem, assuming it arrives, I'm just trying to get an idea on a rough timeline and understanding of this Bren/Alfa-Proj/Ralkem thing.