Billy Butcher is an interesting character. He's a flawed hero. He's not always very nice, but somehow he's still one of the good guys.
I'm curious about him not being played by a cockney.
The character is kind of a parody of the cockney geezer in British gangster movies or something. He's kind of over the top and quite funny. His dialogue is a parody of British swear words -- swearing that's slightly misused, and not quite how British people speak, but also, kind of, yeah, that's how they speak.
I think the character works better because the actor isn't British. And I sort of imagine the character not working well if the actor was British.
He's hilarious though.