In the temporary accommodation block for the homeless, 11-year-old Sam* tells you about life in a flat so cramped that he, his brother, sister, mum and dad can’t all sit in the living room at the same time, or eat at the same table.

Dad, whose restaurant business once provided a happy, stable family home, now lies desperately ill with an inoperable, terminal brain tumour.

Sam and his younger brother share a room, even though everyone accepts they shouldn’t. The ten-year-old younger brother’s recently diagnosed ADHD means he has tantrums that can lead him to get up in the night and attack Sam.

The third bedroom is so crammed with medical equipment for Dad and other storage that there is hardly any space for Sam’s older sister, who has just turned 18.

At a time when the family desperately wants to be together during Dad’s final months, Sam’s much-loved older sister – “really helpful, she looks after me, the best” - has had to spend weekdays away at her grandmother’s so she can study for her A-levels.

Sam’s mum says she has been asking for a property that would allow the family to live together since June 2016.

But with social housing now so hard to find, she says she has repeatedly been told: “There’s not enough housing out there for us.”

Bright and articulate, Sam – not his real name - speaks with a poise and politeness that is striking.

You might think he is wise beyond his years, but he might tell you he has no choice.

With Dad ill and sister so often away: “I feel I have to help my mum. There’s no-one else to help her.”

He checks on his dad every night, “to make sure he is all right.”

His mum had to stop him from selling his toys: “I thought maybe I could use the money to buy Dad a gift. I want to see my dad more happy and stuff.”

Mum talks about him feeling he has to be the man of the house, but Sam is still just a boy, who only weeks ago finished primary school.

When he describes his lowest moment, last Christmas, when everyone else seemed so happy, he falters.

“I felt … I felt … I just wanted to … I didn’t want to be in this world.”

The fear is that all over the country there are more and more children like Sam.

Last week the Local Government Association (LGA) reported that the number of homeless children stuck in temporary accommodation had increased by more than a third in three years to reach 120,540.

The Department for Communities and Local Government countered that the number of children living in temporary accommodation was down from its 2006 peak, and said central Government was investing £550 million to help tackle homelessness.

But Labour MPs said the Government should “hang its head in shame” at an alleged increase that equated to an average of 906 more children – almost an entire secondary school’s worth - becoming homeless every month for three years.

The LGA said that the current situation was unsustainable, and called for central Government to support councils by allowing them to invest more in building genuinely affordable homes.

And now the charity Action for Children, which is trying to help Sam and his family, has also claimed the situation is deteriorating.

Carol Iddon, the charity’s managing director of operations, told The Independent: “In the absence of social housing, more and more families across the UK who are struggling to make ends meet are facing housing crises and, increasingly, homelessness.”

She added: “It can be a very lonely, even embarrassing time, which young people find difficult to talk about. Sometimes all it takes to help them cope with this incredibly difficult situation is for someone to listen to what they are going through, and to offer practical help and support.

“We mustn’t forget the devastating impact that losing their home and being placed in homeless accommodation, through no fault of their own, can have on young children.”

The causes of homelessness Show all 7 1 /7 The causes of homelessness The causes of homelessness Family Breakdown Relationship breakdown, usually between young people and their parents or step-parents, is a major cause of youth homelessness. Around six in ten young people who come to Centrepoint say they had to leave home because of arguments, relationship breakdown or being told to leave. Many have experienced long-term problems at home, often involving violence, leaving them without the family support networks that most of us take for granted The causes of homelessness Complex needs Young people who come to Centrepoint face a range of different and complex problems. More than a third have a mental health issue, such as depression and anxiety, another third need to tackle issues with substance misuse. A similar proportion also need to improve their physical health. These problems often overlap, making it more difficult for young people to access help and increasing the chances of them becoming homeless Getty/iStock The causes of homelessness Deprivation Young people's chances of having to leave home are higher in areas of high deprivation and poor prospects for employment and education. Many of those who experience long spells of poverty can get into problem debt, which makes it harder for them to access housing Getty Images/iStockphoto The causes of homelessness Gang Crime Homeless young people are often affected by gang-related problems. In some cases, it becomes too dangerous to stay in their local area meaning they can end up homeless. One in six young people at Centrepoint have been involved in or affected by gang crime Getty Images/iStockphoto The causes of homelessness Exclusion From School Not being in education can make it much more difficult for young people to access help with problems at home or health problems. Missing out on formal education can also make it more difficult for them to move into work Getty Images/iStockphoto The causes of homelessness Leaving Care Almost a quarter of young people at Centrepoint have been in care. They often have little choice but to deal with the challenges and responsibilities of living independently at a young age. Traumas faced in their early lives make care leavers some of the most vulnerable young people in our communities, with higher chances of poor outcomes in education, employment and housing. Their additional needs mean they require a higher level of support to maintain their accommodation Getty Images/iStockphoto The causes of homelessness Refugees Around 13 per cent of young people at Centrepoint are refugees or have leave to remain, meaning it isn't safe to return home. This includes young people who come to the UK as unaccompanied minors, fleeing violence or persecution in their own country. After being granted asylum, young people sometimes find themselves with nowhere to go and can end up homeless Getty Images/iStockphoto

It is hard to argue about the impact that homelessness has had on Sam.

You ask him how he would explain to a friend what homelessness is like.

“Hard, miserable, upsetting,” he says. “It’s hard for me to deal with this. I just wish everything was back to normal.”

Normality, now, seems like a golden age – Dad running a profitable restaurant business, the whole family together in a terraced house in Cardiff.

“It was an amazing house,” says Sam. “It was fun. We used to go to the park with my dad and my brother, playing football or cricket.

“I felt happy, free. It was the best family I could ever wish for.

“Now it’s gone a bit upside down.”

Dad’s brain tumour was diagnosed in 2007. For years, treatment seemed to be keeping it under control.

But then in 2015, the father became so seriously ill he could no longer continue running the restaurant.

With Mum having to look after three children and a very ill husband, they asked someone they thought they could trust to run the restaurant on their behalf. And things went badly wrong.

“He didn’t pay any bills for a year,” says Sam’s mother, “And we only found out he was doing this when the bailiffs came to disconnect the gas from the restaurant.”

Bailiffs began turning up at the family home, demanding money for the unpaid business debts. One tried to remove the television as Sam and his younger brother were watching it. The two boys offered him all the money in their piggy banks to stop him taking it.

By May 2016 the family had no choice but to sell their home for £118,000. After they paid off the mortgage company and creditors, says Sam’s mother, “We didn’t have a single penny left.”

They sofa surfed at her sister’s house before Cardiff Council moved them into a block of flats that provides temporary accommodation for the homeless in June 2016.

They have been there ever since.

“You never think it is going to be you,” says Sam’s mother. “We always had our own house, our own car. Now not even the chairs we sit on belong to us.”

Yes, she agrees, she has an intelligent son.

“But he keeps on saying, ‘Mum, what’s the point of being intelligent when you have nothing?’”

Sam tells you his nights are disturbed by the ADHD of his brother in the bed next to him. The opportunities for trips to the park are far fewer. Seeking the support of friends is far from straightforward.

“I don’t really like my friends knowing I live here,” says Sam. “I feel embarrassed, and scared sometimes.

“I don’t know how they are going to react when I tell them. I worry we might not be friends any more.”

So far, he has told only close friends.

They are, he says, “fine about it”.

But they are all going to one secondary school. Sam, now out of the catchment area, will be starting at another comprehensive: “No-one I know is going there. I’m scared…”

Cardiff Council accepts that because of the younger brother’s recently diagnosed ADHD – of which the authority had been unaware when it placed the family in temporary accommodation – there is a genuine need for a permanent home in a four-bedroom property.

But there is nothing within the three or four-mile radius that would keep the mother near supportive friends and family as her husband passes away, or allow her to get the boys to two different schools in something like good time once the carers had arrived in the morning to look after Dad.

And so they are stuck, and growing increasingly convinced there is no way out of temporary accommodation.

“I feel upset and angry,” says Sam. “I am really worried that we will stay in this situation, and in this place, for a long time – until I am grown up.”

He talks wistfully of once more of having a home big enough to invite friends round, of maybe one day even having a garden to play football in.

But most of all he talks about his desperately ill father.

Because they are in temporary council accommodation, they can’t adapt the flat to allow for his ever-increasing levels of disability and frailty.

In the past six months, Sam and his mother have had to call paramedics three times to help with lifting Dad – a full-grown man – after falls.

“It’s not good for him to be staying here,” says Sam. “I think it is dangerous for my dad. I am quite scared.”

Most of all - for his dying father’s sake, as much as his own – Sam wants them to be a united family again, living under the same roof.

“My sister’s not here,” he says. “I would love to live with my whole family and see them every day, play games with them.

“I want us all to be in the same house, spending more time with my dad. I want my dad more happy…”

Cardiff Council says it is doing everything it can. Lynda Thorne, the cabinet member for housing and communities, said the council finds permanent homes for most households in temporary accommodation within six months.

“The council,” she added, “Has committed to delivering 1,000 new council homes over the next five years and has recently had its application to suspend the Right to Buy approved by Welsh Government with an aim of safeguarding much needed housing stock for the future.

“The way in which we deliver services to homeless households with dependent children is an absolute priority.”

But the councillor’s statement also spells out the challenges in trying to find homes for children like Sam.

“The number of families with children being placed in temporary accommodation has increased by nearly 12 per cent over the past two years,” says Ms Thorne, “Despite an increase in the success of homelessness prevention activity.

“Cardiff has a very high level of housing need for all types of accommodation with more than 8,000 applicants on the waiting list for social housing - 4,600 of them in significant housing need.

“Our homelessness service is facing increased pressure largely due to private sector landlords who are leaving the rental market combined with the impact of welfare reform changes such as the benefit cap.”

And in the middle of it all is Sam, wishing for a home where the whole family can live, while his father is still there.

When you ask what he wants for his 12th birthday, there is only one answer.

“For us to be a proper family again.”