Cathy Powell was an expectant mother who gave birth to triplets, appearing in Series 1, Episode 6. She is portrayed by Tina O'Brien.
On her birthday, Cathy met a big, handsome sailor named Billy, and later found out she was pregnant. Later, she says it was her pink stilettos (and therefore, presumably, her legs) that attracted him to her in the first place. The two tried to keep in touch through letters (as he lived in Poplar and she lived in Hull), but, according to Cathy, he was terrible at keeping up.
Seven months and two weeks later, Cathy traveled to Poplar to surprise Billy, only to find his decrepit flat empty. However, she was not worried, as she says he's probably out at sea and forgot to write to her. It can be assumed that Billy knew she was pregnant, because, of course, they stayed in touch.
Cathy attends the antenatal clinic and is seen by Nurse Lee, who checked her in as a new patient and asked her how far along she is. Cathy immediately responds that she's exactly seven months, two weeks. Jenny looks at Cathy's very big bump and says that she looks to be farther along, but Cathy is adamant the dates are correct. When she reaches up to rub her belly, Jenny sees that she's unmarried, and at her look, Cathy simply says their unmarried status will quickly change when Billy returns.
Impatient, in case Billy returns while she's gone, Cathy leaves the clinic when Jenny goes to tend to a fainted woman.
A few days later, alone in Billy's flat, Cathy's active baby kicks her rather hard, and she jokes that if he keeps up, he'll have to deal with his father.
Later that night, Cathy's pains get worse, and she realizes she's in labour. She goes to the telephone box and phones Nonnatus House. Chummy answers and Cathy fearfully explains the situation as the contractions pass. She gives her address and Chummy promises to be there in 15 minutes. Chummy advises that she go back home and wait for her, but the contractions become too powerful and Cathy doubles over against a wall after ending the call.
As Chummy races to the apartment building, the delivery pack falls from her bike and is destroyed. Not having any other option, Chummy carries on and finds Cathy outside on the ground. Together, they make their way back up to Billy's apartment and Chummy is dismayed to find it filthy, without electricity or water and poorly furnished. Cathy directs Chummy to some candles and the nurse tells her to take off her underwear and lay back with her heels to her bottom, knees wide apart. Chummy apologizes and says it must feel strange, to which Cathy jokes "How d'you think I ended up like this?".
Chummy says that she wants to call an ambulance so that Cathy can have the baby in hospital, but Cathy begins screaming with another contraction and Chummy realizes it's too late. Cathy soon gives birth to a baby boy, and, much to Chummy's surprise, he's "a dainty little thing".
The candles begin to burn out as Cathy holds her son. She remarks on how much the infant looks like his father, and how Billy made her feel "small in his arms". This strikes a chord with Chummy, who just recently broke up with Peter, due only to the fact that her mother disliked him.
Another pain comes on and Chummy tries to assure the new mother that it's only the placenta. But as the pain gets worse, Cathy asks if it's supposed to hurt so much, and Chummy listens to her belly with her Pinard and realizes it's twins. This shocks Cathy, but she appears more horrified at having to go through birth all over again. The second baby is born, another boy, and the last of the candles goes out.
Chummy races downstairs, attempting to get the light off of her bicycle, but gives up quickly when Cathy starts to scream again, picking up the entire bike and hauling it upstairs. Now with light, Chummy goes to Cathy's side, who is whimpering on how much it hurts. Chummy once more believes it's the afterbirth, but again finds out that Cathy is having another baby. Like before, Cathy is horrified.
This last birth was the hardest for Cathy, who was exhausted and in extreme pain all through every birth (it must be noted that Cathy was likely unprepared for birth). She screams at Chummy that she can't do it, but with Chummy's encouragement, she gives birth to her third baby boy. With nothing more to wrap the baby in, Chummy takes off her uniform, and wraps the baby in that. She is now just wearing a petticoat.
As Cathy recovers, she tells Chummy that that night she had with Billy was the happiest of her life. She says that with him, she felt she had so much life in her, more than she ever had growing up. Cathy explains that she had a chance at love and took it, and it turned out to be "the best and bravest thing I ever did", especially so now that she has three baby boys.
Cathy's speech emboldens Chummy, encouraging her to mend things with Peter, to take love with both hands and hold on tight, despite what her snobby mother thinks of him. She leaves Cathy after the labour is finished and heads to the police station to find Peter. She and Peter reunite, much to their joy, and later marry, going on to have a son.
Throughout the episode, we the audience, are not meant to be optimistic in Billy returning to Cathy, just as Chummy is not optimistic in her relationship with Peter after her mother arrives. But at the end, both relationships are shown to have thrived, despite the lack of faith others had in them.
We last see Cathy walking down the street to Chummy and Peter's wedding, wearing her high heels and pushing a pram. She stops, turns and tells Billy, who is holding their third son, to hurry up. Billy smiles at her, and goes beside her so she can take his arm.