Found some screencaps of her in "Schoolboy Father", and she is writing with her left hand. However in every episode of FOL and her TV movies she is right handed. Is she ambidextrous? To my knowledge never knew she was left handed.

http://lostinthepast.shunpike.net/a/ASS16/SbF291.jpg
http://lostinthepast.shunpike.net/a/ASS16/SbF292.jpg
http://lostinthepast.shunpike.net/a/ASS16/SbF294.jpg

Perhaps it was more esthetically pleasing that way? If she used her right hand, you wouldn't be able to see her writing.

That is what I was thinking too. I bet if someone interviewed Nancy and asked her about that she would simply say the director asked her to fake writing left handed.