The most important thing is to have a sensitive, effective detection system that everyone has agreed to implement. Self-harmers are often secretive and good at avoiding detection, so it is important that staff know what to look out for. PE teachers might be the most likely to spot physical injury, while form tutors and learning support assistants can spot behavioural changes. Non-teaching staff need to be part of the same process, have the same training and get the same support. When children are distressed they go somewhere on their own, such as the toilets. The only people moving around school in teaching time are non-teaching staff, so it’s crucial that they feel part of the process. Even more effective, however, is encouraging pupils to come forward and voice concerns about their friends to tutors or heads of year, or any adult they feel confident with.

Once you know, or suspect, a child is self-harming then it is important someone is available for them to talk to. Our year heads have nine lessons a week when they’re around for pupil support, and their offices are accessible at all times. Assistant heads of year have a reduced timetable, and our office staff, deputy and assistant headteachers are all easily accessible. No pupil should ever be in a position to claim that “no one was available” or “no one was interested”. This is, of course, expensive: we spend around pound;250,000 a year on staff time, management allowances and teacher support to make the system secure.

We also try to include a proactive element of guidance so that children have the skills to understand themselves and to prepare them for something like self-harm. It is included within our PSME (personal social and moral education) curriculum and dealt with in depth in Years 9 and 10, at the age when it is most likely to occur. We also include self-harm in the peer-counselling programme. It’s important to provide support for the friends of the self-harmer. It can be bewildering and frightening if a friend comes to confide in them, and they need to be confident to come to us without feeling they will land their friend in trouble.

Some examples show just how flexible a successful system has to be. In one case, parents alerted the school about a child who was self-harming and we were able to work together with them, and welfare providers, to get to the root of the problem, which was bullying. In another case, a form tutor challenged a pupil sympathetically about marks on her arms. She confided that forthcoming exams were making her stressed. In a third case, it was other pupils who alerted their head of year. Eventually, after many denials, the self-harmer admitted that her problems were family related. It turned out to be a child protection issue that finally resulted in her being taken into care and fostered for her own protection.

One common factor is that all the pupils were relieved when their problems were finally recognised, and they began to get support. We worked hard with the relevant authorities andor families to ensure they remained within the school community, felt safe and secure and could achieve their best. The same kind of support needs to be given to parents. We always contact parents if we know their child is self-harming, with the urgent recommendation that they contact their GP. Involving parents is a difficult issue we have discussed in detail, but, on balance, we believe the immediate welfare of the child is more important than confidentiality.

We have appointed a full-time health service practitioner. Previously, anyone who was self-harming had to be referred outside school, but now there is an independent on-site professional in whom pupils can confide.

Unlike a busy GP, they have time to talk.

While we are part of multi-agency liaison, you cannot leave it to others.

Other agencies - child protection, the police, social services and welfare officers - only see a child once they’ve got a problem or are a problem.

Schools see children differently: when they’re not, or before they’ve got, a problem. We are uniquely situated to help them build confidence in themselves and the people around them.

Paul Strong is headteacher of William Farr CE school, Wilton, Lincoln