1931 Ladies 6AF with Center second hand. Not seen one before

 I was recently given the watch below as it wasn't working and it was going to be junked. 'NO' I said. Give it here. Not personally seen a ladies this early with a central second hand.  Got it back to working ways so thought i'd let you guys see it and see if you have any idea of a model name.

Strange the movement says 6AF and that bulova didn't give it a different calibre number (although there may just be enough space next to the f for another letter but a wheel is covering it, but I don't think so)  

Only down side is a 3 letter inscription on the hinged back.

Tiny Tiny Lugs too eh!