When nine-year-old Adeboye Falode grows up, he wants to be on The X Factor. "I want to be a singer," he says in a broad Irish accent. "Or a footballer." He says it with a shamefaced little smile, as if he is already aware that his life will not work out like that. Currently, Adeboye is under lock and key at Yarl's Wood Immigration Removal Centre, along with his mother, Aderonke, and his brothers Adedire, 12, and Adebowale, 14.
In order to get from the visitors' area to their room in the "family unit", Adeboye and his brothers must pass through up to ten locked doors and undergo a search. "They make you feel like a criminal, when you haven't done anything wrong," says Adebowale. Like the 2,000 other children who pass through the UK's immigration removal centres each year, they have no access to primary NHS care if they fall ill. The food they are given each day consists primarily of chips and rice: "It's disgusting." They have all been taken out of school - particularly worrying for Adebowale, who was studying for his GCSEs next year. He wants to be a doctor. "I just want to go to school and do normal work," he says. How will he feel if he is still in detention this Christmas? "I'll probably explode."
When I meet the Falodes in the visiting area at Yarl's Wood, they have been told they are due for "removal" to Nigeria the following day. "I don't want to sleep because I know they [the guards] will come in the night or first thing in the morning," says the boys' mother. Aderonke is terrified that the guards will try to drug her in order to stop her resisting deportation; Adebowale tells me that he knows another child who was carried unconscious from his cell after hiding under the bed to resist removal. "They had injected him with something," he says. Such rumours abound in Yarl's Wood - Gill Butler, a member of the Yarl's Wood Befrienders' Group, has heard many similar stories. Although difficult to substantiate, they are an insight into the fear and insecurity the place instils in detainees. "If you are not strong, you will go mad in here," says Aderonke. "There is no peace of mind."
The family is planning to resist removal. "Even if Gordon Brown himself called me I would not go," says Aderonke. The boys have been issued with careful instructions: when the men come in the night, they should get into the van quietly, because if they make a fuss they might get hurt during the journey. Only when they reach the safety of the airport should they start to shout and scream. "The children want to resist," says Aderonke. "They just want to go back to school and to their friends. They don't want to go to Nigeria." The Falodes had been living in Belfast for a year before they were detained, having fled Nigeria when the boys' father died. "I was being harassed and threatened by my late husband's family. They wanted me to marry my brother-in-law, and to take the children as slaves." In Belfast, the boys were doing well at school and had joined a local church. "Everyone was so welcoming. Last Christmas, they gave the boys presents, and we made them African food. We were so happy."
The Falodes' appeal for asylum is unlikely to be successful, as their case is based around a domestic dispute rather than political persecution. (The UK asylum system is often criticised for prioritising the type of claims made by men, who are more likely to be directly involved in politics, and treating problems faced by women, such as domestic and sexual violence, less seriously.) But even if they are to be refused, Adebowale points out: "Why couldn't they just let us stay in a house until they reach a decision?"
The official reason for detaining those whose asylum case has been refused is to prevent them from absconding prior to removal. But the European Commissioner for Human Rights, reporting on detention of children in the UK immigration system in 2005, found: "Prima facie . . . families with their children attending school are less likely to abscond [if their asylum claim is refused] than any other category." Families are easy pickings for a government obsessed with meeting deportation targets.
In detaining children for immigration reasons, the UK breaches the UN Convention on the Rights of the Child. Children can be detained for an unlimited time without charge or trial. In a report entitled No Place for a Child, Save the Children found that detained children suffer from "weight loss, lack of sleep, skin complaints and persistent respiratory conditions. Children often suffer from depression and changes in behaviour in detention."
Butler, a former nurse who has visited dozens of families in Yarl's Wood, says: "The mental health effects [on children] are devastating. You see bedwetting, nightmares and post-traumatic stress disorder. Imagine the trauma for a child of being woken up in the early hours by eight to ten officers and taken away from home."
Recently, 14-year-old Meltem Avcil, who had been in Yarl's Wood for three months, was transferred to Bedford Hospital after entering into a suicide pact with another detainee and cutting her wrists. Meltem is Kurdish, but had been living in the UK for six years before she was detained. She was even tually released following an intervention by the Children's Commissioner for England, Professor Al Aynsley-Green. "Looking at the immigration system, one is forced to ask: what does the government's slogan 'Every Child Matters' actually mean?" says Adrian Matthews, Aynsley-Green's senior policy adviser on asylum. "It is outrageous that increasingly, children with immigration issues seem to be excluded from that. Things are not considered from the child's perspective in taking the decision to detain . . . [children's] lives are picked up and torn apart."
In 2005, Aynsley-Green produced a report based on a visit to Yarl's Wood, in which he expressed grave doubts about the welfare of children at the centre, remarking: "It is not possible to ensure that children detained in Yarl's Wood stay healthy, stay safe, enjoy and achieve, make a positive contribution, and achieve economic well-being." However, says Matthews, the commissioner's call for far-reaching reforms went unheeded by the government. "Following our visit, Yarl's Wood did make some small changes, such as replacing the barred cell doors," he says. "However, on the wider issue there has been very little progress."
Once the Falodes have been escorted out of the visitors' hall by a guard, I meet Comfort Adefowoju and her daughters Adesola, ten, Olasubomi, seven, and Sarah, seven months, and son Adedapo, five. Sarah, a tiny, lively baby, has livid red eczema all over her face which, Comfort tells me, she has not been able to get any medicine for. "They don't even provide enough formula. It is four o'clock, and Sarah has only had one bottle so far today." On the first day, Comfort spent the last of her money on formula, but now she has completely run out. "If I can't even buy milk for the baby, how am I going to get a solicitor?"
The Adefowojus were picked up from their home in Belfast - they attended the same church as the Falodes - early in the morning and, as is usual practice, told they had to leave immediately. "We didn't have time to get any clothes," says Adesola. "I only brought two pairs of unders, and I don't have any socks." She and her sister have spent the freezing cold winter days - during which they were first transported from Belfast to the Dungavel detention centre in Scotland, then transferred to Yarl's Wood - wearing just a pair of sandals on their bare feet. Olasubomi is wearing a tattered vest and no jumper.
"The children don't understand what is happening," says Comfort. "They were saying to me, 'Are we criminals?'" The family fled Nigeria after Comfort's husband borrowed money from a politician that he was unable to pay back; he ran away, leaving Comfort to deal with the thugs sent to the family home to collect the money. "They threatened to firebomb the house and kidnap the children," she says. University-educated and previously a successful entrepreneur, Comfort was forced out of the house and business she had helped to build. "If they send us back, there is no way these children will not be destitute," she says. "I tell you one thing: they will put us on that plane over my dead body."
The Adefowojus were threatened with removal barely three days after being taken into detention - leaving no time to get legal representation. They managed to resist, but, like the other families in immigration detention this Christmas, they live in fear of another early-morning knock on their cell door.
What can you do?
The New Statesman will report further on children in immigration detention in the New Year. If you are concerned and would like to help, consider doing the following:
Write to Al Aynsley-Green, the Children's Commissioner, expressing your support for his work with children in detention centres, and urging him to continue putting pressure on the government to stop detaining children for immigration reasons. Email: info.request@11MILLION.org.uk 
Join a visitors' group. For more information about visiting detainees in Yarl's Wood, see: http://www.ywbefrienders.org 
For details of latest campaigns, check the websites of the following pressure groups: Medical Justice Network, which campaigns for detainees' rights - www.medicaljustice.org.uk  - and the National Coalition of Anti-Deportation Campaigns - http://www.ncadc.org.uk