Final character biographies, from PBS.org.

SISTER BERNADETTE (Laura Main)

SISTER BERNADETTE is still in her 30's, the closest in age to JENNY and the other secular midwives. A consummate professional, she has a fresh, uncomplicated approach to her work and connects well with JENNY and her other younger colleagues.

Laura on Sister Bernadette: “She is closer in age to the younger ones so there is perhaps a bit more understanding between them, and there’s one episode where she gets a little bit involved in what’s happening with them and the romances that are going on. That’s actually been fun as it’s a different side to her.”

TRIXIE (Helen George)

NURSE TRIXIE FRANKLIN is a bright, glamorous girl in her mid-twenties who is already living and working at Nonnatus House when JENNY arrives. Wearing fully-fashioned nylons and lush red lipstick, TRIXIE loves jazz and dancing, smokes cigarettes and, it’s fair to say, is a bit of a flirt. She has a much more outgoing disposition than JENNY, but the two share the sense of adventure in their work and become fast friends.

Helen on Trixie: “She’s the fun-loving, party-going midwife who’s always up for a drink and a smoke and to go out dancing with the boys. She relishes trying to set up her fellow midwives with other guys and push them into relationships and get them married off, but with a twinkle in her eye. Although, fundamentally, she’s a midwife and that’s what she’s there to do.”

CYNTHIA (Bryony Hannah)

NURSE CYNTHIA MILLER, like TRIXIE, is also a resident at Nonnatus House when JENNY appears. Caring, stoic and intelligent, she finds her midwifery work both challenging and rewarding, a highly desirable alternative to the dull domesticity that would otherwise be her only option. Quiet and sensitive, and also in her early twenties, CYNTHIA becomes JENNY’s confidante and life-long friend.

Bryony on Cynthia: “She’s not terribly experienced as a midwife, she’s still learning, but she’s very conscientious and really wants to do well. She puts everything into it. She’s quite shy but she grows through the series and becomes much better friends with Jenny as it goes on.”

CHUMMY (Miranda Hart)

CAMILLA CHOLOMONDELY-BROWNE, otherwise known as Chummy, is the daughter of a prominent family who has found her way into nursing and midwifery by a circuitous route. Eternally good-humored and monumentally kind, Chummy is crippled by lack of self-confidence. Her great height and physical clumsiness plays its part, but a loveless childhood spent in boarding schools has made the greater impact. An adept midwife, she is hampered by acute shyness and, perhaps more crucially, a complete inability to ride a bike. Chummy soon wins the hearts of her colleagues, but her struggle for self-belief will threaten to capsize her.

Miranda on Chummy: “She comes from a very upper class background and she has decided that her calling from God is to be a midwife, so, she comes to the east end to join Nonnatus House much to the horror of her viceroy father and her upper crust mother.”