Some of the greatest defensive fighters ever came pre 1940. Pep did nothing but praise Benny Leonard as one example. Fighting with hands low does not mean you are easy to hit. The idea is to use boxing techniques such as slipping, ducking, parrying, feinting to make an opponent miss and have ones fists in ready to counter.
Thanks to everyone who has contributed. My journey starts Monday with Willie Pep, I'm then going to have another look at Bernard Hopkins as he's been incredibly relevant in my lifetime (I was born in 1976), and then I'm going to spoil myself and have a look at the fighter who got me into this sport in 1985, Marvin Hagler. Please keep the suggestions coming. Thank you all once again.