I know Loreon I Lannister was the very first Lannister to rule as King of the rock but of course it doesn't mean he was the very first person to ever bear the name Lannister.
I'm trying to find out which descendant of Lann was the first person to derive the name "Lannister" from the name "Lann". The book doesn't mention who the first Lannisters were before Loreon's time?
Even if Lann the clever was just a historical myth, it's obvious someone used his first name as an idea to formulate the name Lannister. Question is who?