Kareem is 11-years old. About the same age as my daughter. On Wednesday he went missing.

I met him just two weeks ago in Calais. He was wandering around by the old bus British volunteers are using as a kind of school, wearing a bright pink sweatshirt someone had given him. He had been in the camp several months - alone with no one looking after him.What struck me wasn't just his vulnerability but his desperate search for comfort and affection.

He followed round the British volunteers he knew, giving them hugs, making jokes. We talked a bit, and he hugged us before we left too. No one is quite sure how he got there from Afghanistan or where his parents are.

Through the winter months this child has been sleeping in a tent in Calais - no parent, no guardian, no action from the French Government, no outcry from the British Government. And then on Wednesday he disappeared. Aid workers have been told he was seen climbing on to a ferry bound for Kent. No missing persons report has been filed by the French authorities, so British charities contacted the Children's Commissioner to get the Kent police and social services to help.

Whatever you think about people climbing illegally onto ferries, whatever you think about whether the French or British Government is at fault, whatever you think about refugees, just think on this: the child is eleven. He has endured months alone in a cold tent vulnerable to traffickers, abuse, prostitution, and risking his life to find someone to care for him.

And it's not just Kareem. Charities identified around 400 unaccompanied children and teenagers in the Calais jungle. Many of them have family in the UK - but the legal process to reunite them takes months. Many have been trafficked. Some of them are taking crazy risks each night trying to jump on the back of trains, lorries or ferries. Most have scabies or bronchitis.

Inside the camps in Calais Show all 20 1 /20 Inside the camps in Calais Inside the camps in Calais A Kurdish child and her father get out of their tent in the makeshift migrant camp in Grande-Synthe near Dunkerque Inside the camps in Calais Kurdish migrants works around the tents of the makeshift migrant camp in Grande-Synthe near Dunkerque Inside the camps in Calais Volunteers from Holland set up a bridge of fortune over the mud using pallets of the makeshift migrant camp in Grande-Synthe near Dunkerque Inside the camps in Calais Refugees walk among tents in a makeshift camp as containers (rear) are put into place to house several hundred migrants living in what is known as the "Jungle", a squalid sprawling camp in Calais Inside the camps in Calais A makeshift camp is seen in front of containers (rear) put into place to house several hundred migrants living in what is known as the "Jungle", a squalid sprawling camp in Calais Inside the camps in Calais Inside the camps in Calais Inside the camps in Calais Inside the camps in Calais Inside the camps in Calais Inside the camps in Calais Asylum seekers in Calais The camp near Calais harbour where refugees from the Middle East and central Asia congregate to attempt the crossing from France to the UK Justin Sutcliffe Inside the camps in Calais Asylum seekers in Calais Most of the temporary residents in this camp are from Afghanistan, Pakistan, Syria or the Kurdish administered regions Justin Sutcliffe Inside the camps in Calais Asylum seekers in Calais Camp residents cook and share food at their site just outside Calais Justin Sutcliffe Inside the camps in Calais Asylum seekers in Calais A group walk through the camp near Calais Justin Sutcliffe Inside the camps in Calais Asylum seekers in Calais Most of the temporary residents in this camp are from Afghanistan, Pakistan, Syria or the Kurdish administered regions Inside the camps in Calais Asylum seekers in Calais A 16 year old immigrant from Eritrea tries to brace himself against the rain and cold by sheltering under the road bridge Justin Sutcliffe Inside the camps in Calais Asylum seekers in Calais Rubbish strewn on the ground near one of the campsites Inside the camps in Calais Asylum seekers in Calais A man stands among the tents at the campsite just outside Calais, France Inside the camps in Calais Asylum seekers in Calais A camp near Calais harbour where migrants from the East africa congregate to attempt the crossing from France to the UK. Most of the temporary residents in this camp are from Eritrea. Inside the camps in Calais Asylum seekers in Calais Graffiti depicting the dangerous journey trying to smuggle onto a lorry to the UK

Now, Help Refugees say a third of these children have gone missing in the weeks since the French authorities began clearing the camp. As we warned, no provision was put in place to support these young people. Now neither the charities nor the authorities know where they have gone.

According to Europol, 10,000 out of an estimated 26,000 unaccompanied child and teenage refugees in Europe have gone missing as a result of the refugee crisis.

On Friday, we learnt that teenager Mohammed had died beneath the wheels of a lorry. In January 15-year-old Masud died in the back of a lorry. Both boys were trying to reach family here in the UK.

Too many children have died taking desperate risks to find someone to keep them safe, too many have disappeared into the hands of criminal gangs. It is not enough to blame the French or expect Greece or Italy to do it all. Britain should do its bit to help children too.

The French must put in place proper child protection. But British Ministers should be putting urgent pressure on the French to act, as well as sorting out the broken family reunification system for those with relatives here. And alongside other European countries, Britain should do its bit and take some of the lost children like Kareem.

Labour peer Alf Dubs was one of 10,000 Jewish children Britain rescued from the Nazis through the Kindertransport.

His amendment, calling for Britain to take in 3,000 unaccompanied child refugees from Europe will be voted on by MPs in the coming weeks.

Two weeks ago, when I pressed the Prime Minister to accept Lord Dubs's amendment, he refused to do so, saying other countries should take all the responsibility instead.

Yesterday Kareem was found in Kent. Social services are now trying to help him. But how many more children must go missing or die on European soil before the Prime Minister reconsiders these words?