The scale of child trafficking into the UK may not be fully known, with UN children's agency Unicef saying thousands may be brought into the country every year.
Children are smuggled in to work as prostitutes
But while scant record keeping makes the number of victims unclear, the level of suffering on an individual level can be seen by talking to those children who have suffered at the hands of the people smugglers.
One of those victims - a 15-year-old Albanian girl who was forced into prostitution in the UK after being tricked into a bigamous marriage - spoke to BBC Radio 4's Today programme.
"I stayed at home with him thinking I was his wife, but then I started to have doubts because when he had guests or friends coming to the house he hid me," she said.
"He understood I knew the truth so he started to threaten me.
"He hit me with a mobile phone charger and he said he would cut me into pieces and throw the pieces in a forest."
She said the experience left her feeling like she no longer wanted to live.
"I hated myself, I wanted to be dead. I thought I was at the lowest level of society.
"I thought people know, and they really are disgusted knowing what I am, knowing I am a prostitute."
David Bull, executive director of Unicef UK, said more needed to be done to stop the trafficking of children into the country.
He told the BBC the children were often not spotted at airports or ports as they had good cover stories, false documents or were travelling with people who claimed to be relatives.
He said: "There needs to be very good specialist training for immigration officers and social workers and police and people who come into contact with these children so that they are more aware with the problem and better able to identify the children who are victims of trafficking."
He also called for more safe houses to be created for children rescued from traffickers.
His call came as the only existing safe house for smuggled children, in West Sussex, faces closure.
The house, which mainly takes children from West Africa who were being smuggled into Gatwick airport, will shut down after the county council decided it was not cost effective.