At least 10,000 children in care were placed in potentially unsafe accommodation including caravans, tents and barges, a Sky News investigation has found.
Figures obtained under the Freedom of Information Act show that local councils used unregulated accommodation to house vulnerable children - even though these settings were not subject to inspection or regulation by Ofsted.
Between January 2019 and December 2020, at least 9,990 children were placed into unregulated accommodation by 86 local authorities. At least 20 children were sent to live in tents or caravans, 17 were placed into hostels, and seven were housed in barges on canals.
Now, the government says a ban on the use of unregulated homes for under-16s will come into force in September.
It comes after a year-long consultation into the housing of children in the care system.
Education Secretary Gavin Williamson said: "Vulnerable children under 16 are too young for the type of accommodation that provides a place to stay but not the care and support that they need. The action taken today, supported by the sector and in response to their views, is an important step in making sure children in care are placed in settings that give them the highest chances of success."
But the move has already angered many campaigners who had hoped the government would extend the ban to those up to 18 years of age.
Carolyne Willow, director of the care rights group Article 39, said: "The education secretary states in his foreword that he cannot imagine a circumstance in which a child under the age of 16 would be put somewhere where they don't receive care.
"But children aged 16 and 17 also need care. Today's shameful policy announcement entrenches a two-tier care system. Children who live with foster carers are already entitled to remain part of these families until they are 21.
"Yet the government is saying today that it is entirely legitimate for children who don't live with their own family or a foster family to be denied care from their 16th birthday."
In response, the government says it will introduce national standards for unregulated settings that are accommodating 16 and 17-year-old children in care, and care leavers.
Ashleigh was 15 when her foster placement broke down and social services had to find her a placement. At first, she was taken to a hotel for the night where she had to share a room with two support workers.
A day later, she was sent to live in the home of someone she had never met before, and was taken to a caravan park a few weeks later.
"When I was in the caravan, I felt pure fear. It was my third move in just over a month. My GCSEs had finished and I knew that I hadn't achieved well because of everything that was going on."
Ashleigh told Sky News that while she was staying in the caravan, the people who lived next door gave her home-brewed alcohol and that her support workers allowed it to happen, even though she was underage.
"I drank it. The support staff did as well. I went round to the next door caravan on my own.
"After a few drinks I got lightheaded. I felt like I was going to pass out. I heard them lock the door from the inside. I knew something wasn't right. I panicked. I managed to get out and ran. They started chasing me. I've never felt in so much danger as I did in that moment."
The next day, Ashleigh says she told her social worker what happened.
"She told me there was nowhere else for me to go. I had to stay in the caravan."
The care of children is in crisis, partly due to a national shortage of regulated children's homes. Council have relied heavily on unregulated accommodation as a way of housing vulnerable children.
Anne Longfield, the children's commissioner for England, told Sky News that she had urged the secretary of state to ban unregulated accommodation for under-18s.
"I asked him to go further and actually ban that provision for any child under 18 because they are the most vulnerable children who need the most support.
"Unregulated provision is what it says on the tin. These are places where there will obviously be very vulnerable children who often will be sharing accommodation with older adults.
"There may be addiction issues, there may be drugs, there may be criminality.
"There should be no instance where a child under the age of 18 who is in the care of the state should be left without proper supervision, proper support and the regulation around it to ensure that they are safeguarded against harm."
An independent review into children's social care system is now under way, headed by Josh MacAllister.
A former teacher, Mr MacAlister founded the social work charity Frontline in 2013. He will step down from his role as chief executive to lead the review.
"The basic test for me is whether we can create a system which better guarantees for every single child growing up in England safety, stability and love as the bedrock of being able to go on and have a successful future and there are lots of things at the moment which are an obstacle to that."
Some charities say the government needs to consider implementing the ban on unregulated care for children up until their 18th birthday because they are children, not adults.
Sam Turner, policy manager at Become, a charity for children in care and young care leavers, said: "Parents of 16 and 17 year olds don't suddenly change the style of parenting when they reach that age. They don't move them to somewhere else at the age of 16.
"But that's exactly what the government is suggesting should be the norm.
"The reality under the government's proposals is that those who are 16 and over can expect to receive a lower level of support than others. And we don't think that's right at all."