Kathleen Richards knows how lucky she is to be alive. In 1979, she woke up in bed to find the serial killer Fred West on top of her. It was by no means the first time West had assaulted the 17-year-old, but it was the last. This time, she managed to escape from the room she was renting at 25 Cromwell Street, perhaps Britain’s most notorious address, where Fred and Rose West raped, tortured and murdered so many girls and young women. Fred West took his own life in January 1995 while on remand, charged with 12 murders. Rose West was convicted of 10 murders later that year and is serving a whole-life sentence.

In her own way, Richards has also been serving a life sentence. Today, she is a youthful, likable and traumatised 65-year-old. How could she not be damaged by all she experienced? Although she gave vital evidence at Rose West’s trial that helped get her convicted, she never told the police what Fred had subjected her to. Nor did she tell her nearest and dearest. She couldn’t. She didn’t know how to. Now, almost half a century later, she has written a memoir, Under Their Roof, that does so much more than chronicle her time living with the Wests. It’s a desperately sad insight into what makes someone vulnerable to abusers, and why victims are often abused multiple times by different people. But ultimately, this is a book about the triumph – however painful and even fluky – of good over evil.

We meet at the London office of her publisher. She is with her daughter Hannah, here for support. Richards speaks with a broad Irish accent despite having spent most of her life in England. She is immaculate in an understated way – smart long shaggy bob, pristine white shirt. Not surprisingly, she is nervous.

Richards’ story starts in 1960, when she was born in Dublin to poor, uneducated, ferociously strict parents. Her father, who sold scrap and firewood from a horse and cart, spent what little money he had on himself, while his children were underfed, underloved and regularly beaten. She was the fourth of 10 and grew up sharing a bed with her siblings. At school her nickname was Smelly because of the urine-soaked clothes she wore. She kept the family home meticulously clean, but was never thanked for it. The only present she received from her parents was a naked, one-legged dolly her father had picked up at the dump that she called Polly and adored.

One day in the summer holidays, hungrier than ever without the daily currant bun and glass of milk they got at school, she and her older sister Deirdre nicked some apples and ran for it. They found themselves in the grounds of a local factory, whose middle-aged caretaker told her he had a bag of sweets and would like to give her one. He took her into the hut and said she just had to do one little thing before getting the sweet. He put her hand in his trousers and made her masturbate him, and said next time he would give her a penny. After that, she returned time and again for her penny.

A year later, her maternal grandfather, who lived by himself after her grandmother’s death, took Richards’ hand and asked her to do the same thing for him. He also paid her a penny. With it she bought the sweets her parents denied her – Black Jacks, Fruit Salads, Catherine Wheels, Refreshers. But she hated what she was doing, and began to hate herself. “I told myself I was worth a penny. That’s all. A penny. Or a potato.” On one occasion, her grandfather didn’t have a penny so he paid her with a boiled potato. What made it worse, she says, is that neither man was overtly intimidating. “If they had shouted or threatened me not to tell anybody, I would have felt better about it; that I had no choice. But I did have a choice, didn’t I? I went round there.”

One day, she told her mother what her grandfather had been doing. “I said, ‘Mammy, Grandda’s doing things to me. And I don’t like it, Ma.’ I didn’t know how to say it, I didn’t have the words. She just turned around, so angry with me, and said, ‘Get out, you!’ I just ran out of that flat.” She never mentioned it to her mother again.

The family moved from Dublin to a council house in Derby, then Gloucester. Even though they had far more room than before, Richards’ mother told her when she was 17 that there was no space for her or 18-year-old Deirdre, who had just had a baby. That’s when they moved into the home of Fred and Rose West, who were known for renting out cheap rooms. “People said he’s a friendly, funny, nice guy. He’d help anybody. That’s what he was known for. He’d give you a lift everywhere.” The Wests picked up a number of their victims in the car when they were hitching.

Richards will never forget the first time she met the family. “We thought we’d be safe because there were loads of kids. He brought us in and he stood there and said, ‘This is my wife, Rose, this is my lover, Shirley, and these are all the kids.’ And my first thought was, yeah right, you wish she was your lover, because she was a young girl, really nice looking. She was 17, the same age as me.” Shirley Robinson later confirmed to Richards she was Fred’s lover and that she was carrying his baby, but still she didn’t believe her. How could a girl her own age be with somebody Richards regarded as an old man, and how could his wife have accepted it? The more she discovered about Rose West, the less she believed it possible. Richards says Rose was usually screaming at her husband or children. She found her terrifying.

Richards soon learned there were multiple versions of Rose. One was simpering and prissy. When Richards’ mother visited, Rose would address her in a sugary voice verging on the infantile. Another was boisterous, over-friendly and inebriated. Then there was the Rose that most horrified Richards. One night, Shirley led Richards into the living room and Rose was lying on a sofa in a see-through nightie and garish makeup, watching hardcore pornography and smiling silently at her.

Richards and Shirley became friends. She says Shirley seemed sad and confused. She didn’t appear to have a bedroom and would hang about on the landing. Late one night, she saw her going into the Wests’ bedroom. This was her routine; she shared their bed.

* * *

On their first day at Cromwell Street, Richards, Deirdre and her baby were taken by Fred to their shared room. There were large holes in the wall. They stuffed them with paper, but when they woke up, the paper had been pushed through the holes and was scattered on the floor. This happened every night. They wondered whether Fred was a dirty old man, but preferred to tell themselves it was a game the children played. He appeared inoffensive, comic almost. He walked with a fake limp and constantly forgot which leg he was limping on. He made daft jokes, and worked on his own in the cellar or outside, digging up the patio. Most of the day and night he appeared to be hammering and drilling. “There was definitely something a little odd about Fred, but he seemed harmless enough, like a real-life clown,” Richards writes in Under Their Roof.

She soon discovered a darker side. In the corridor, Fred would stand in her way, tell her there was no room to pass, press himself against her and pinch her bottom. “Lovely arse, girlie,” he would say. The pinches became more violent and left her badly bruised. He would wait for Richards, lunge at her and demand kisses. She says he smelled of “dead animals” and it made her nauseous.

On one occasion, Fred attacked her when she walked through the front door, shoving her into the wall and banging her head against it. His elbow was pressed into her throat, choking her. When she managed to scream, Shirley emerged from the living room and told him to leave her alone. Richards told Deirdre she was terrified of Fred. He never assaulted Deirdre, Richards believes, because her sister was a stronger character. They thought about leaving Cromwell Street but had nowhere to go.

Richards decided to tell the police, but when she got to the station she couldn’t bring herself to go in. She sat outside crying, asking herself what she could accuse him of, telling herself she wouldn’t be believed and she deserved it anyway because she had allowed herself to be abused all those years ago. Fred was a married man with children, he was popular, he probably had friends in the police. “I wanted to say he’s doing things to me, grabbing me, and I thought they’d just say, ‘Is he? OK.’” Instead of going in, she returned to Cromwell Street.

She and Shirley bonded over ice lollies. Richards was working at Wall’s and Shirley loved red ice lollies. On Fridays, she would bring a little box home and they would hang out together eating them. Richards didn’t understand Shirley, but she liked her. “Lovely, she was. Real gentle. She must have had some kind of life before she went there, God help her. See, there’s always someone worse off than yourself, that’s what I say. No matter what I went through, there’s people worse.”

Does she still think about Shirley? Richards swallows and struggles for words. “Yeah.” She starts to cry. “Yeah.”

Her daughter asks if she wants to stop, and passes her a tissue. “D’you want to go outside or are you OK?”

Richards blinks away her tears. “No, I’m OK.”

* * *

After Richards had been with the Wests for a few months, Shirley disappeared. When she asked Fred where she was, he told her she had gone back to family in Germany. Richards and Deirdre thought it was strange. She was just about to have his baby, why would she leave then? Why wouldn’t she have said goodbye? How could she have afforded the flight?

The assaults on Richards grew more regular and brutal after Shirley left. When Deirdre went to visit friends overnight, she dragged the chest of drawers against her door as protection. But it didn’t deter Fred. Another day, when Deirdre and the baby were away, she unlocked her bedroom door to find him lying in wait for her on the bed (he had a spare key). This time, she was saved by one of his friends calling. “Fred West had pushed me on the bed. His hand was over my mouth.” She refers to him as Fred West rather than Fred. She says it creates more distance between her and him.

Once when she tried to escape, Fred and Rose grabbed a hand each and bundled her back inside. A neighbour saw it but did nothing. Another time, when Fred was attacking Richards, her mother dropped by just in time.

All this culminated in the most shocking assault, again when Deirdre and the baby were away. In February 1979, Richards woke up to find Fred in bed with her, his hands all over her. She begged him to let her go. He told her he would so long as she agreed to watch a “special video” with him and Rose, and then he said, “We will have some fun. You get my meaning?” She promised she would, and told him she needed five minutes to clean herself up. After he left her room, she crept to the front door, barefoot and in her pyjamas, nudged it open and bolted to the bus station to wait for Deirdre and the baby to return. When her sister’s bus finally got in, she told her what had happened and said she could never return to Cromwell Street. Deirdre told her they would go back to collect their things and leave first thing in the morning. Richards stood guard all night. The next day, Deirdre moved to Derby to stay with her boyfriend and Richards moved in with her brother Danny.

After she left Cromwell Street, she met a man she liked. He became her first boyfriend and she got pregnant. Richards thought she was too young and messed up to have the baby, so she had an abortion, which led to the end of what had been a happy relationship. Soon after, at 19, she took an overdose. “It was still all in my head. I felt dirty. Ashamed. Worthless.” She thought of all the abuse: the caretaker, her grandfather, West. “I felt as low as anybody could feel. I felt the walls were closing in. What have I got to live for? It was just horrible. All I could see was Fred West’s face. I was hallucinating and his face was there in my face staring, saying, ‘Come on, come on, come on!’” Her brother discovered Richards after she overdosed, and she was taken to hospital.

Richards recovered and moved back to Dublin. She went on to marry and have two children, John and Jess, with her first husband, Callum. When Jess was three, Richards and Callum separated. She says a contributory factor was her problems with intimacy – in bed, she was haunted by images of her abusers. She associated sex with control, pain and shame.

Now a single mother, she moved back to Gloucester; despite the memories of Cromwell Street, most of her family and friends still lived in the city. She and the children quickly settled down. John was at school, Jess was in nursery, and she was peeling onions for a chicken curry when the news bulletin came on the radio. It was early February 1994. The lead story was about a search for human remains in a house in Gloucester. The newsreader said, “Frederick West, aged 52, and his 40-year-old wife, Rosemary, of 25 Cromwell Street, have been arrested on suspicion of multiple murders.”

How did she feel when she heard that? “Absolutely horrific. Complete shock.” She’s welling up. “There weren’t any words. I rang Deirdre, said hello and she said, ‘I know.’ We didn’t speak, just held the phone. I could hear her breathing. She could hear me. I was ill for a long time after that. Stomachaches, headaches. The shock affected my whole body.” She and Deirdre, who died last year, never spoke about West again.

Among the victims, the remains of Shirley Robinson and her baby were found buried in the Wests’ garden. “I thought about Shirley a hell of a lot after they found her. How come I didn’t see that, why did I not know? A million questions.” She pauses. “I might have had that survivor’s guilt,” she says with typical understatement.

Had she thought of Shirley in the intervening years? “Yes, I used to dream of her. She’d be knocking on my door with a baby in her arms.” She sniffs back her tears.

After the discovery of the remains, she saw her past life through a different lens. It became apparent that the Wests had been grooming her as Shirley’s successor. “That’s the scary bit,” Richards says. “I know that now, but obviously then I didn’t.”

She thought about the endless drilling and digging. “We thought he was building a swimming pool. We really did. I remember looking out of the window thinking, it’s not going to be very big. To think what was actually happening, and we were laughing. It’s sick.” She remembered how he had smelt of dead animals, and realised it was probably the stench of his victims.

Did she have nightmares? “I didn’t have dreams. I didn’t sleep much when it all came out.” For how long? “A long, long time.” She thought about it constantly when she was awake. When friends who knew she had lived there asked about it, she’d tell them she’d only been there a few days and seen nothing. But she had lived there about 15 months and seen too much.

The police asked for a witness statement. Richards didn’t say she had been abused, but she told them all she knew about Shirley. Her son overheard some of the conversation and she had to admit to him she had lived in the house. “He ran in saying, ‘So you were living there?’ I hadn’t wanted the children to know.”

It’s amazing to have gone through all that and not burdened your family with it, I say. “That’s the last thing you want to do, isn’t it?” Well, plenty of people would, and it’s incredible you didn’t. Richards smiles. “Is that a compliment?” she asks. “Thank you.” What impact has experiencing such horror had on her life? Again she smiles. “I’m a very busy person. The house is sparkling.”

Richards went into the caring professions, working with elderly people in a home and fostering children. She says fostering in particular has been shaped by her life experience. “I thought I could help these children because I’ve been abused, I’ve been through a lot, maybe I can understand them. And I think I did. At Christmas, one of the social workers came round and saw the tree with all the presents and said, ‘I’m moving in here!’”

“She downplays herself all the time,” Hannah says. “I’ve just never wanted for anything, and nor did the foster children. I was given a perfect childhood.”

Richards looks at her tenderly. “D’you feel loved?”

“Every day!” Hannah says. “Every day! Of course I do.”

Richards says she never felt loved as a child. The opposite. Her mother died a couple of years ago. Did she soften towards the end? “No. And my dad was worse.”

Yet she believes her mother probably saved her life. The Wests picked the most vulnerable people to be their victims – young women who weren’t in touch with their families or were remote from them (as well as their own 16-year-old daughter Heather, Fred’s first wife Catherine Costello and her eight-year-old daughter Charmaine). Only six of the 12 known murder victims had been reported missing. But the Wests knew Richards’ mother was likely to ask questions. “I think if it wasn’t for her coming every now and again, I would have been gone.”

On 1 January 1995, after 11 months in custody awaiting trial, Fred West took his own life. How did Richards feel about that? “At first I was delighted. I thought: great, he’s gone off the planet, he can’t hurt anyone else. Horrible, evil man, you don’t deserve to breathe the same air as us. Then a bit later it was, like, what about all those families? They’re not going to get any justice now.”

In November 1995, Rose West was convicted of 10 murders. She had claimed never to have met some of the victims buried at 25 Cromwell Street, including Shirley Robinson. Richards gave evidence for the prosecution contradicting that. “She sat there saying she didn’t know Shirley, but she did. I knew that. So that helped convict her. When I was in the court, I kept looking over and thinking, I wonder if she remembers me. Then I was terrified in case she did remember and she’d go, ‘Yes, and this happened and this happened.’” Richards was so scared because she still hadn’t told the police she had been abused by Fred.

Helping to secure Rose West’s conviction gave Richards some comfort. But she continued to torment herself about the day she had not been brave enough to report Fred to the police. Even today she still seems to be doing so. “Someone might have listened to me in that police station. Someone might have checked it.”

After the trial, Richards continued with life as before – a great mum, always on the go, a much-loved carer and foster parent. She buried her memories as best she could. But abusers were still not done with her. By 2013, she and her second husband, Mike (Hannah’s father), had grown apart, and they divorced. A few months later, friends encouraged her to go on dating websites. After two dates with one man, he started stalking her. This time, she did report it to the police. Two officers came to take a statement. The male officer, PC Darren Heath, returned to her house by himself the next morning. She thought he must have information, but he didn’t. He started to turn up every day, making inappropriate sexual suggestions. Richards was now in her 50s and yet another man seemed bent on ruining her life. She hid when she saw him outside, and put her house up for sale. When he saw the sign, he uprooted it.

Six weeks after she reported the stalker, three officers turned up at her home. By now, she had lost all trust in the police. But this time it was different. They asked if she’d had any bad experiences with Heath, and told her he’d been reported for harassing vulnerable women who had sought police protection. This time she told them the whole story. In 2015, he pleaded guilty to misconduct in public office by engaging in sexual relationships with three women he had met while on duty; he was sentenced to 45 months in prison. Another narrow escape.

Thankfully, there is a happy ending to Richards’ story. After Heath’s conviction, she was offered therapy by the police, and for the first time she spoke about the guilt she felt that she was still alive and Shirley wasn’t. She still didn’t dare broach the subject of the abuse she had suffered. Meanwhile, she and Mike were becoming closer again. She told him she’d never stopped loving him and he reciprocated. In 2022, they remarried.

She confided to Mike what had really happened to her at 25 Cromwell Street. Richards was still blaming herself. “When I told Mike the first time, I was in a bad way. I said, ‘If I’d only gone into the police station that day … ’ and Mike was, like, ‘Well they wouldn’t have listened to you. Another girl had gone to the police, and they didn’t listen to her.’” This is true: Caroline Owens, one of the Wests’ nannies, was abducted, raped and abused by the pair in 1973. She reported the crimes to the police, but the Wests inexplicably got off with a £50 fine. “It was only when he told me that that I thought, OK, maybe they wouldn’t have listened to me.”

She told friends about what she had suffered at the hands of Fred and Rose West. All were supportive. They told Richards her story could help others who have been abused. She began to understand why she’d been unable to talk about it. On the one hand, she was ashamed of what she had been through; on the other, she felt she hadn’t suffered enough to consider herself a victim.

But writing the book has been cathartic. “I was able to say something I’ve never been able to say today.” She looks so proud, but at the same time so diffident. What was it, I ask? “I was able to say I was sexually assaulted by him. I just said it out loud.” She comes to a stop. “I haven’t healed yet, have I?” she asks quietly.

• Under Their Roof by Kathleen Richards with Ann Cusack is published by Sphere, an imprint of Little, Brown, at £22. To support the Guardian, order your copy at guardianbookshop.com. Delivery charges may apply.