“We get more calls about youngsters at the end of May and in June than at other times,’’ says Sophie Woodforde, spokeswoman for the National Missing Persons Helpline (NMPH). At the end of April this year the helpline’s workload increased by 20 per cent as children baulked at going back to school for the summer term. Another surge is likely in September as the autumn term begins.

Many people think about running away from home at some point in their youth, but the minority that do so place themselves in grave danger. “The potential risk of abuse cannot be stressed enough,’’ says Catherine Davies,the helpline’s schools visitor. “Teachers and parents often don’t realise what stress they are putting kids under. They don’t realise what can happen to these children when they do run away. There are people hanging around train stations just waiting for young kids on their own with their bags to walk down the platform. This isn’t scaremongering. Stand in a major station for a while. There are people there who are not waiting for a train. ”

Children who run away risk being physically abused, or ending up on the streets or in prostitution. (There are only four safe hostels for under-age runaways in the country.) Under-17s are the most vulnerable group. According to research by National Children’s Homes, Action for Children, 43,000 under-17s go missing every year, some more than once. There are around 100,000 runaway “incidents” in Britain each year.

Catherine Davies was approached by a young girl recently after she had spoken about the helpline in a school assembly. “The girl felt under pressure from exams,” she says. “Her family owned a business and they expected her to do well at school, but also to work in the business. The child could see no way out. She was involved in discussions about it with a teacher, but she said if there were no changes she would run away.”

Because so many schools were calling on the NMPH to give talks, and to underline the grave dangers of running away, a schools pack is being piloted in 900 state and private schools in London and in 400 major secondary schools nationally. The NMPH is developing a partnership with the London borough of Wandsworth, under which educationists and child psychologists will publicise the problem. The helpline is hoping that many more initiatives can be launched once feedback from the pilot study has been monitored.

Sixty per cent of children who run away are missing for no more than 24 hours and tend to stay in the local area with friends. A further 15 per cent go missing for up to 48 hours. Only two per cent are missing for more than 14 days.

Among the last group is a boy who went missing during his A-levels two years ago and has never returned. His parents are still searching. Then there is Lisa, a 15-year-old from a middle-class home in Norfolk who had no strong reason for running away except that she was bored at school. She travelled to London and was picked up by a man who persuaded her to beg for him on the streets to feed his heroin addiction. She was on the streets for three months. During this time her father found her but couldn’t persuade her to go home. “Eventually she built up a relationship with NMPH,’’ says Ms Woodforde. “She would ring us and tell us she was all right and eventually she went back home. She called that period her ‘funny phase’; we hear of that a lot.”

Then there is David, a 14-year-old from Portsmouth, whose mother had died,who was quarrelling with his stepmother and not doing well at school. He ran away to London and went to social security, claiming he was 17, came from a family of travellers and needed a National Insurance number. He went on to get a job on a farm, took driving lessons and opened a bank account. Eventually he was traced and now lives in his local area, near but not with his family.

The schools pack includes general information and role play aimed at making children consider the dangers and how their actions will affect their families. The helpline acknowledges that some children have to run away because of abuse at home, but if all children can be encouraged to talk to an adult, such as a teacher, this might help them avoid getting into further trouble.

Angela Glister, who teaches English and drama and is head of lower school at Tadcaster Grammar School in North Yorkshire, has used role play from the schools pack to develop powerful and convincing drama.

Gwendolyn, a Year 9 pupil, played the part of a mother. She says: “I realised how upsetting it must be for the parents, and also how many people leave home, never to return. I think I now will be able to help any of my friends if they ever wanted to leave home.’’

The National Missing Persons Helpline can be contacted on 0500 700 700