Door handle removal problem

[Gold Digger]

On a 1930 tudor I can't get the right side door handle to come out. It's an old locking style and I wonder if there is some kind of clip on the square shaft to lock it in place to keep some one from pulling it off the door and breaking in. Can't find anything on this in any of my books. I read some place to turn the handle to the left a quarter turn and it will come out but this want turn to the left.