MPs are calling on the government to apologise to women who were coerced into handing over their babies for adoption in Britain in the 1950s and 60s.

More than 20 MPs have backed a motion recognising the “pain and suffering” of women forced to give up their babies. Their move follows the government’s rejection last year of a demand for a public inquiry.

The group, led by Labour MPs Alison McGovern and Stephen Twigg, will take its case for a debate to the backbench business committee on Tuesday. The move is supported by MPs from Labour, the Conservatives, the Lib Dems and the SNP.

More than half a million children were given up for adoption at a time when “unmarried mothers” were often rejected by their families and ostracised by society. Adoptions were generally handled through agencies run by the Church of England, the Roman Catholic church and the Salvation Army.

Many of the women who have since gone public with their stories say they were pressured to give away their babies.

These women suffered a terrible injustice and it should not be forgotten or ignored Alison McGovern, MP

Jill Killington, 68, told the Observer: “I was never asked whether I wanted to go ahead with the adoption. It was a fait accompli.

“Nobody gave me any information about support or benefits, even though these would have been available at the time.”

Veronica Smith, 77, said: “No one ever said I could keep [my baby].”

McGovern said: “After meeting with women who were cast away from their families and communities, and then forcibly separated from their babies, I am determined that their experiences need to be heard. These women suffered a terrible injustice and it must not be forgotten or ignored.

“By holding this debate, I hope we can show that this parliament recognises the pain the state and its institutions caused.”

Referring to an apology made less than two weeks ago by the Irish prime minister, Leo Varadkar, for 126 illegal adoptions between 1946 and 1969, Twigg said: “This debate will provide the British government with an opportunity to right a historic wrong and apologise to those British mothers and children who were adopted under similar circumstances.”

Varadkar told the Irish parliament that the illegal adoptions were “another chapter from the very dark history of our country”. According to campaigners, the figure was the tip of the iceberg. His statement followed an apology five years earlier for the Irish state’s collusion in the Magdalene laundries, run by the Catholic church to house “fallen women”. Many had their babies forcibly removed and put up for adoption.

The treatment of single pregnant women and forced adoptions in Ireland was highlighted in the 2013 film Philomena, starring Judi Dench. However, similar practices in the UK have received far less attention.

According to Bhatt Murphy, a firm of solicitors representing some of the women in the UK who were pressured into having their babies adopted, the impact has been devastating and continuing. All of the firm’s clients report feeling a profound sense of loss and distress, and some have experienced serious mental health crises.

In a television documentary broadcast in November 2016, Cardinal Vincent Nichols, the head of the Roman Catholic church in England and Wales, apologised for the church’s role in the “hurt” caused to women.

He said: “The practices of all adoption agencies, whether religious, charitable or state … were sometimes lacking in care and sensitivity. We apologise for the hurt caused by agencies acting in the name of the Catholic church.”

The Church of England and the Salvation Army also expressed regret for the pain inflicted. “What was thought to be the right thing to do at the time has caused great hurt. That is a matter of great regret,” said a church spokesperson.

In rejecting the demand for a public inquiry last August, children’s minister Robert Goodwill said: “While a public inquiry may offer those affected an opportunity to have their voices heard and give them a sense of justice, I have formed the view that this provides insufficient justification for a public inquiry.”

An inquiry was unlikely to uncover new facts or lead to legislative changes, Goodwill said, and it would be very costly,

Campaigners have continued to demand acknowledgement of their treatment as well as an apology from the government.

Veronica Smith managed to trace her daughter 24 years after being forced to give her up. Photograph: Mark Pain/The Observer

Veronica Smith, 77

Brought up a devout Catholic, Veronica, right, felt she had no choice other than to obey her family. She gave up her newborn baby girl, Angela

I was 24 years old and working as a nurse at Butlin’s holiday camp when I got pregnant. It was 1964, before the pill and before [the legalisation of] terminations.

I was in shock: I really didn’t know what to do. I had been brought up as a Catholic – my father was very devout – and obedience was the number one thing.

I told my mother and my sister about it. They came to see me and said it had all been sorted. They arranged for me to go to a hostel in south London run by the [Catholic] Crusade of Rescue.

I stayed there for six months, doing housework and scrubbing floors. I can’t really remember much about this time.

My daughter was born in March, and she was with me in hospital for about a week. I knew from the start that she was going for adoption. No one ever said I could keep her.

I called her Angela. It must have been very hard for me to say goodbye to her, but it’s a blank in my head. I was told to just get on with my life. I never had any more news about her.

In the late 1980s I had a nervous breakdown, and all this grief came flooding out. I managed to trace my daughter, who was 24 by then. This helped my recovery.

It has blighted my life. I had no further children, and I didn’t get married until 12 years ago. It’s a big injustice. The churches and the authorities have a lot to answer for.

Felicity Davies at home in West Wirral. Photograph: Gary Calton/The Observer

Jill Killington, 68

At the mother and baby home 16-year-old Jill visited with her parents, pregnant women were made to scrub floors and go to church. She was later made to give away her nine-day-old son

I was 16 and in a steady relationship with my boyfriend. We had talked about getting married, but our parents were opposed to that. When I found out that I was pregnant, my parents were extremely upset. Then they just took over.

Our GP put them in touch with a social worker from the Church Army, who liaised with the adoption society. I was never asked whether I wanted to go ahead with the adoption: it was a fait accompli. Nobody gave me any information about support or benefits, even though these would have been available at the time.

My parents took me to visit a church-affiliated mother and baby home. There were pregnant women scrubbing the floors. They were made to wear wedding rings and go to church, where they had to sit at the back. I remember sobbing my heart out on the way home.

My parents let me stay at home on condition I gave up my baby. Not once did anyone give me an alternative.

My son was born in December 1967. I called him Liam. He was with me for nine days, but we had to take him to the foster carer on Christmas Eve. I was inconsolable. The foster carer allowed me to visit him.

Me, my parents and the baby travelled to London on the train for the adoption. I held him in my arms all the way. A lady came into the room and admired him, and asked if she could hold him. The moment she had him, she told me to kiss him goodbye and she was out of the door.

I was expected to just go on with my life as though nothing had happened. My parents never spoke of it again. I had one photograph of Liam, and I kept it always.

When he turned 18, the only gift I could give him was to put my name on the contact register. It was another nine years before he got in touch. When I got the letter, I knew what it was even before opening it. He had had a lot of issues in his young life, which is not unusual for adoptees.

I’m certain it has had an impact on my life. There’s a cycle of grief and anger. A kind of melancholy is always there in the back of your mind, even if you have a happy marriage and more children. A nagging presence.

Felicity Davies, 64

Pregnant at 15, Felicity was badly assaulted by her mother when she told her. She gave up her baby, Mary, but managed to find her, years later

I was 15 when I found I was pregnant. My mother lost the plot when I told her – she tried to push me down the stairs, hit me across the face with a poker, broke a couple of ribs.

I was sent to Chaddeslode House in Shrewsbury, a home for unmarried mothers run by the Church of England. It was full of young women having babies. But there was no information or education about it. We’d get up at 6am, go to the chapel for prayers, then start our “duties” – cleaning and laundry. We became quite docile and institutionalised.

Adoption was taken for granted; there was never any suggestion that there might be an alternative. I’ve beaten myself up about it for years.

My daughter was born early and was very tiny. I called her Mary. No one at the hospital knew she was for adoption. I had her a couple of weeks before the social workers realised.

The moment of goodbye was awful. I remember standing outside the hospital waiting for a bus and feeling a part of me was missing.

I married Mary’s father and we went on to have more children. We are still married. Much later I tried to trace Mary, but just came up against brick walls. Then one day I got a phone call from a private detective who my daughter had hired to find me. We met when she was nearly 40, and had children of her own.

[The adoption] was an incredibly painful experience. The feeling of loss persisted and caused me pain and unresolved deep anger for many years until I had help to resolve it. To a large extent it defined who and what I am. In lots of ways I’ve been very fortunate compared with other women, whose lives have been destroyed by [adoptions].

Attitudes to women like me were astonishing. It wasn’t that far removed from when they used to lock unmarried pregnant women up for life. It makes me very angry.

I’d like an acknowledgement of the suffering these women have been through. A lot of it is tied up with the churches: it was under their authority that these things happened. Nothing can compensate for the loss, but an acknowledgement is what we need.