When Sheila Joyce turned ten, she was given her first ever birthday present. Not a Barbie doll or a new dress but a trip to a local cookery school.

She was excited because it was her first day out alone with her mother Mary. An escape from the freezing four-bedroom bungalow she shared with her parents and 15 siblings in an impoverished suburb of Drogheda, about 30 miles north of Dublin.

On arrival, a group of 'beautiful women' swept her away to their spotless kitchen, told her she was 'special' and lavished her with freshly baked bread, buns and cakes — unimaginable treats for a little girl whose family could barely afford to buy groceries.

She could hardly believe her luck. But the welcoming embrace of the cookery school on that December day in 1979 was a sinister facade. Far from providing sanctuary from her bleak family life, it proved to be the first step towards becoming what she describes as a 'slave' for the secretive Catholic sect Opus Dei.

More than three decades have passed since she escaped but still Sheila bears the scars left by the cilice, the spiked metal garter she was forced to wear for two hours a day as an act of penance.

Biting into her thigh like barbed wire, it has left a row of unsightly bumps, testament to her seven years of silent servitude at Opus Dei's Lismullin Conference Centre, adjacent to the cookery school and hidden by trees in remote countryside about half an hour's drive from Drogheda.

Told that her vocation lay in being an 'assistant numerary' — essentially a domestic servant — Sheila worked seven days a week, getting up each morning at 6am, kissing the ground and saying 'Serviam' (Latin for 'I will serve').

And serve she certainly did. There followed a draining round of serving breakfast, cleaning the guests' rooms, washing their clothes, waiting on table at lunch and dinner, tidying the chapel and laundering the priests' vestments.

Every day she had to pray for two and a half hours and only got to bed at 10pm, ready to start the whole gruelling cycle again.

The assistants were allowed to see their families only once a year and for Sheila there was no divine inspiration in this unpaid drudgery, just psychological torture that drove her to contemplate the unthinkable.

'There was a rule where if you were raped you were automatically expelled,' she says. 'So I remember trying to explore how I could expose myself to that.'

As we will see, even this was not the most desperate measure she considered.

Now 56 and a separated mother-of-two, Sheila still lives in Drogheda. Dressed smartly in a trouser suit for our interview, in a living room tellingly devoid of the religious imagery often found in Catholic homes, she clearly finds it upsetting to relive her experiences.

She's doing so because she was so angered by the findings of a recent investigation into Opus Dei by the Mail, revealing just how little has changed in this most controversial of organisations.

Set up in 1928 by Spanish priest Josemaría Escrivá, later accused of supporting the bloody dictatorship of General Franco, it teaches that holiness can be achieved through the mundane tasks of everyday life (Opus Dei being Latin for 'God's work').

With nearly 100,000 members worldwide, some 500 of them in the UK and 4,400 in the US, the sect has long refuted its portrayal in Dan Brown's 2003 best-selling book The Da Vinci Code, dismissing the suggestion that it is a sinister, vindictive and violent sect as 'malicious nonsense'.

But more recently it has faced horrifying allegations of abuse against women around the world and in the UK our reporter found that there are still disturbing echoes of Margaret Atwood's dystopian novel The Handmaid's Tale.

With its tentacles reaching as far as Britain's university campuses, Opus Dei recruits vulnerable young women to centres like Lakefield Hospitality College, an affiliated catering school in affluent Hampstead, north London.

Posing as a prospective student, I learned that it's home to a small group of girls who have committed to lifelong celibacy and given up career aspirations to act as domestic servants in neighbouring Netherhall House, an all-male hall of residence which is also run by Opus Dei.

Just as Sheila did at Lismullin, these often highly educated young women do the cooking, cleaning, and laundry for the undergraduates and priests who live there but are banned from speaking to or even being seen by them, unless they are waiting on their tables.

Earlier this month, it was announced that Pedro Ballester, a former resident of Netherhall and a member of Opus Dei, has been put forward for canonisation by the organisation.

The chemical engineering student from Manchester has been nominated because of the faith and bravery he showed in battling the pelvic cancer which claimed the 21-year-old's life in 2018.

An Opus Dei website making the case for his sainthood is full of stories of people who have been uplifted by him, or believe he has answered their prayers.

It's alarming for those who have endured life as an assistant numerary to think that his canonisation might attract yet more recruits to an organisation which relegates women to such subservient roles.

'I worry for these girls,' says Sheila who has been in therapy for many years but has still buried a lot of what happened to her.

'I'm not sure I would be able to process all of that, particularly when I think about my own two boys.

'I was a child when I first went to that cookery school. How could they do what they did to a child?'

Her memories are all the more traumatic for knowing that it was her mother who offered her up for exploitation.

While her father Paddy, a struggling farmer, has never belonged to the Opus Dei, Mary was one of its 'supernumeraries' — devotees who live not in the organisation's various institutions, but in their own homes.

'All members have a spiritual duty to recruit and she used her own children to do so,' says Sheila.

'My father left the running of the house and the care of the children to my mother. He either didn't care about what happened to us, or was asleep at the wheel, or both.'

The seventh child in Paddy and Mary's huge brood, Sheila looked forward to visiting the cookery school each Saturday and particularly enjoyed the interest taken in her by the assistant numeraries.

'They were probably only about 18 or 19 themselves but they were adults to me and I wasn't used to getting adult attention.

'The environment was comfortable, it was clean, it was welcoming. I wasn't used to that either. We're talking about poverty so even access to food wasn't regular and we didn't have heating. So to go somewhere warm and have somebody make cakes for us felt very special.'

As the weeks passed, the assistant numeraries got down to business, giving each of the girls a card bearing the image of Opus Dei founder Josemaría Escrivá and suggesting that they should pray to him.

There were also lessons teaching them the catechism — the tenets of the Catholic faith — and so these sessions continued, every Saturday until Sheila was 14.

'That was when they ramped things up. I was assigned an assistant numerary who talked to me more intensely, and told me that I had a vocation and God wanted this for me.

'I started to feel trapped but I thought that if my mother trusted them then maybe I should too.'

While her friends were discovering the joys of school dances and days out in town, Sheila was working at the conference centre all day and caring for her younger brothers and sisters at night.

At 15, she was taken out of school by her mother, just before sitting her exams. According to Sheila, the sect encourages this to keep female followers ignorant, isolated and completely reliant on their teachings.

In 1985, her mother told 16-year-old Sheila that she no longer had a place in the family home and would be moving into the Lismullin centre full time. It was then that her nightmare truly began.

For the next six years, Sheila spent every day at the command of senior staff, including the numeraries — members who live in their centres but work in the outside world and donate their salaries to Opus Dei.

Wearing maid's uniforms as they waited at table, the assistants were forbidden to address or even make eye contact with those they were serving and had to hide behind a screen in between courses.

If they were too slow in getting to the table, they would be summoned by a bell — and admonished for being lazy.

As for their own food, the assistants were given the leftovers from the previous day.

In stark contrast to the affection she enjoyed on arriving at the cookery school, her superiors constantly reminded Sheila she was 'nothing' and made her take part in self-harm rituals in imitation of the sufferings of Christ.

Alongside wearing the cilice, the assistant numeraries had to take cold showers, sleep on the floor, and lash themselves on the bare back and buttocks with a small whip called a 'discipline'.

At first, Sheila had no salary but as she got older, she was allowed to spend a maximum of £5 — around £19 today — on essentials like sanitary towels. Until then, she'd had to request them from the numeraries who kept them in a locked cupboard.

Every penny spent had to be recorded and reported back to the centre's director, so it felt like control masquerading as independence.

'It's slavery,' she says. 'Forcing people to work without any financial reward is slavery.'

By the time she was 18, Sheila was constantly contemplating suicide. But she somehow felt indebted to her abusers who had plucked her from poverty and given her clean sheets and a warm bed.

'I had to attempt to take my life in a way that didn't look like Opus Dei were to blame. I was quite protective of them.

'So I thought of starvation, anorexia. I even looked at scurvy, going through food-related scenarios that would kill me but wouldn't look like it was suicide.'

While there were no locked doors preventing the assistants from leaving, they were terrified of the consequences if they did.

'They used scary, threatening language, like telling you that you would go to hell, and face damnation. And they know they have you trapped because you don't have any formal education completed.'

Those threats were also used to ensnare her sister Margaret who is two years younger than Sheila and, like her, moved into Lismullin when she was 16.

Today they still live around the corner from each other in Drogheda where divorcee Margaret's home is filled with pictures of her two sons and the artwork they created for her over the years.

She and Sheila are close and talk all the time. But at Lismullin socialising was discouraged, with the assistants made to give each other 'fraternal corrections' for even the most minor infractions, like forgetting to genuflect when they passed the chapel.

'Fraternal corrections are where you have to snitch on your colleagues,' explains Margaret. 'It was a way of stopping you forming attachments, and it left you feeling horrible.'

Eventually, Margaret developed a stomach ulcer from stress and poor circulation from being on her feet all day.

'The bottoms of my legs were deep purple and the cilice was very painful when you were working hard, down on your knees scrubbing showers.'

'You tied it on tight because you were worried about it slipping off your leg when you were waiting at table.

'I used to feel so exhausted and isolated. I never got to see my family and all the time I was worrying whether I was doing things right.

'It wasn't even about God, it was always about the teachings of the Opus Dei founder who they put on this huge pedestal. The work was physical abuse, but the way they controlled your mind was mental abuse.'

With no say in where they lived, the sisters were eventually relocated to different centres in Dublin.

Sheila was sent to Opus Dei's all-female Rathmore Residence where she continued to do menial work for students and young professionals while becoming increasingly angry about the life forced upon her.

Every year ahead of their annual vow renewal Sheila would beg to leave. When she turned 22, her abusers finally granted her wish and kicked her out, penniless, homeless and into the arms of the woman responsible for her suffering – her mother.

She said: 'By then, I had been in Opus Dei for seven years. I had nothing. They called my mother to come and pick me up. I felt like I had been dumped back on her lap. She didn't say anything, she seemed to have no response.'

Living back at home in Drogheda, she found work in a Dublin nursing home, where one day she received a whispered phone call from Margaret who was working at Crannton Catering College in another part of the city.

There she had been entrusted with recruiting young female students to Opus Dei, just as she had been groomed herself.

'I used to go with these girls to their cookery classes on Saturdays and they would take me to the pub and all of a sudden I was having a great time. They were such good fun.

'I started seeing what the outside world was like and realising there was more to life than this.'

It took her six months to find the courage but shortly after her 21st birthday, she waited until the rest of the assistants were in Mass and made that call to Sheila, telling her she was planning to leave.

'She met me at a pub at the bottom of the road and she was delighted and completely there for me.'

Margaret says that Opus Dei did 'absolutely everything they could to try and stop me.' And even after she'd left, and started enjoying an independent life, working in a hospital in Dublin and living with an uncle, she was being 'stalked' by her former abusers.

'Opus Dei waited for me every day outside the hospital, just standing there,' she says.

'When I told my uncle, he bought me a bike so I could get past them as quick as I could. Eventually I told them I would call the guards [the police] and they never came back.'

After leaving Opus Dei, Margaret went on to become an accountant, and Sheila has had various jobs in catering and care homes. Both experienced abusive relationships with men — their lack of confidence making them an easy target. Meanwhile, they say, Opus Dei has continued to monitor their actions.

'Our mother is still a member and they use her as an information source and still try and get in touch,' says Sheila.

'When I was at home for Christmas in 2023, she said that someone from the cookery school wanted to see me, and that was the end of our relationship really.'

Responding to Margaret and Sheila's claims, Opus Dei told the Mail that there were 'many inaccuracies in the allegations' but failed to specify what they were. They said they were 'truly sorry if anyone feels hurt or had negative experiences while a member', adding that 'assistant numeraries are highly respected members who help make Opus Dei into a loving family where everyone is cared for and loved.

'As Catholics, we believe that any job can be a way to love God and others, and that it is the love with which it is done that makes it more worthwhile in God's eyes.'

For both Margaret and Sheila, such an interpretation of their suffering is all the harder to stomach because Opus Dei continues to target young girls in Ireland as part of their 'Fearless for Teens 13-16' initiative, promising them 'fun, friendship and faith.'

Activities currently advertised on the website include 'Cookery & Leadership' courses at the Lismullin Conference Centre — aimed at helping participants 'truly unlock their potential' and 'be the best version' of themselves.

If the 'best version' of a young woman is to be a mop-bearing minion, then that's certainly a promise Opus Dei is delivering on and both Margaret and Sheila are determined to warn people away from the Lismullin cookery school and similar establishments.

'Speaking out isn't going to help me,' says Sheila. 'But I'm happy to do it if it makes these young women more aware of just what they're getting into.'