Sister Winifred is introduced at the beginning of Series Three. She is portrayed by Victoria Yeates.
She is the same age as Jenny, Trixie and Cynthia. Prior to coming to Nonnatus House, she was already familiar with Sister Evangelina, whom she met on Evangelina's summer holiday at the village school. She reveals that she previously worked as a head inspector, or a nit nurse, which led to the children nicknaming her "Nitty Nora the Scalp Explorer", probably because there aren't many things that rhyme with Winifred. Before becoming a nun, nurse and midwife, Sister Winifred was a teacher, and loved her job greatly.
Though kind and good-hearted, Sister Winifred possesses some conservative view points common for people of the 1950s and '60s. She very much disapproves of homosexuality, citing sternly that "sodomy is a sin" and doesn't seem to think that homosexuals can love each other. She also is very loyal to her former profession as a teacher, judging a fellow teacher for her affair with a married man, thereby disgracing her profession. Sister Winifred also does not approve of having men present in the birthing room, saying that with new appliances, "we don't even need them to boil water anymore".
At the beginning of her stay at Nonnatus, Sister Winifred is shown to be uncertain of midwifery in general, later telling one of the other nurses that she doesn't get the same feeling of joy out of it as the others do. She also is shown to be uneasy helping women give birth, unsure of herself and saying less than helpful things. However, after being left to help a young Jewish woman give birth, Sister Winifred finds the strength and courage to deliver the baby and comes to enjoy midwifery.
In Series Six, Sister Winifred asks Nurse Crane to teach her how to drive. In the first episode of Series Seven, Sister Winifred passes her driving test.