What does it mean when a guy says Mr Gentleman was my father You can call me then put his name?

Answer 1

The short answer is that it means he's kind of a dork, but that's probably not particularly helpful, so read on.

In the US for the last few decades, it's been common practice for people who know each other to call each other by their first name except in a few unusual circumstances. For example, many people still call their boss "Mr. Surname" even if they've been working for him for years unless he has given specific permission to call him Joe (or whatever his first name or nickname is), and it's almost never considered proper for a student to call a teacher by first name. Even if you're related or he's a close family friend and you know him as "Uncle Joe" outside of school, in class it would still be "Mr. Surname."

"Mr Surname is my father" is a reference to the fact that this wasn't always common practice. Before ... oh, let's say the 1960s ... it was fairly common even for people who knew each other to address each other as "Mr. Surname" (or possibly less formally just "Surname"). Only fairly close friends would be on a "first-name basis" with each other. So, for people Of a Certain Age, "Mr. Surname" really was how their father was normally addressed, and almost certainly how he was addressed by their friends. Kids in the 1950s wouldn't have dreamed of calling a friend's dad by his first name ... watch Leave it to Beaver, and you'll never see anyone under the age of 30 call Beaver's dad "Ward," it's always "Mr. Cleaver."

A person saying this is attempting, in a fairly trite way, to say "You don't need to be formal with me."

A variation is that some people who have either earned a title or are entitled to one due to their position may say something like "Mr. Surname is my father; you may call me Firstname or Doctor/Judge/Mayor Surname." I mean, if you're going to insist on being formal, you may as well be formal properly.