Well, sure, but he's also taught that being gentlemanly, according to Hemingway, is this:Quoting Skitch (view post)
"There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self."
When the protagonist questions if he can be a gentleman with his lower-class accent, this is how his mentor responds. So, at the very least, the question of what constitutes a gentleman is up for discussion and adapts to suit each individual. This seems to be a common theme in stories like this. The mentee learns the rules, but also learns to bend them to suit their own personality. Arya Stark, The Bride, Po (Kung Fu Panda) ... etc. I would say more, but I'm conscious of adding to Irish's word count.