One of the all-time greatest romantic movies ever. Maureen was on Larry King promoting her bio,
'Tis Herself, King brings up the scene at the end of the movie where she whispers something into The Duke's ear, he turns with the stunned look, she grins and then heads off to the house, "What did you say to him?" She will NOT tell us!! She said Ford directed her specifically, he wanted her to say something, as she put it, "simply dreadfully filthy", she couldn't do it. He demanded she say it, because, whatever it was, he knew that Wayne would give the camera the very look that he did.
She has promised to let us know posthumously, if I recall it correctly, she is leaving the information in her will. But she won't let us know while she's still around, classy lady!