When I was growing up, most boys had nicknamed versions of their names, usually a shortened version of their full name with "-y"/"-ie" added. Edward became Eddie, Thomas was Tommy, Mark was Markie, and so on. Usually when you got to be twelve or so, you dropped the "-y"/"-ie" at the end. Now if you're named "William" you are usually called "William" from an early age (rather than "Willie" or "Billy").
When did that old practice stop?