This week sees the publication of a Green Paper about children and young people at risk - of harm, of offending, of under-achievement and of social exclusion.

We know how these risks reinforce one another and that further education is often asked to deal with a package. But what does it mean to re-engage a very troubled and disaffected young learner? What does re-engagement look like and how do we respond?

Do we misread the signs? Do we have the capacity to make the right response? Recent experience at Lewisham College deepens our doubts about getting it right.

We know that some extremely vulnerable and out-of-school young people come back into education through FE. They may not have attended school regularly - or indeed at all - for years.

College may be different enough to try again but any kind of structured learning demands some core behaviours. There is still an expectation that you will attend, turn up on time, listen to teaching staff and fellow students, join in planned activities and keep a grip on your impulses, especially your temper.

Many colleges, certainly those in London, are reporting a rise in the behaviours that fall outside this baseline. We know of students whose actions suggest they cannot stay and they cannot go. They are young people whose angry rejection of what we offer frames the ways they behave in class, in the corridors and in the canteen - but who do not walk away. Is there a kind of engagement here that demands a different kind of response?

Alice, for example, has recently been excluded from Lewisham College, an establishment known for and proud of its record on inclusion. The exclusion followed a history of disciplinary action and a final confrontation with a fellow student that involved a blade, an ambulance and the police.

Every strand of the college’s support systems, confirmed as outstanding in the last inspection, had been used to weave a safety net for Alice. Some help she had refused, some she had ignored. All students are left in no doubt that the college will act firmly to defend the safety of their fellows.

What did Alice expect? The surprise was not the decision to exclude or the fact that it had reached this point, but the vehemence of Alice’s appeal against the decision. She was desperate to hold on to the opportunity she had so often rubbished and abused.

Alice is not alone. In the same month, Beverley was excluded after screaming abuse at her head of school and threatening several members of staff.

This was not a single outburst but a torrent of abuse that continued for 20 minutes before she was escorted from the building.

The trigger for this outburst was a request that she produce her college pass, like every other student, on entering the building. Beverley’s pass was at the bottom of her bag and, instead of recognising this as a universal and daily request, she experienced it as insulting, provocative and unjust.

The stand-off escalated to a point that gave senior staff little option but to exclude. Beverley also made a spirited appeal against the exclusion.

Alice and Beverley have both been accused of bullying by other students.

Both could be dominating and disruptive in class, shouting, spitting and stomping out. They drained the energy of committed teachers, and introduced fear into that relationship.

Both had agreed behaviour improvement targets with their tutors that were reinforced by learning contracts. Neither was able to make use of the personal support offered again and again. Each had complained of being picked on and treated unfairly. And yet, they kept coming. Attendance was good and, in Alice’s case, 100 per cent.

In fact, in the period running up to exclusion, things were beginning to turn around for Alice. The teaching team had managed rudeness, disruption, lateness, even drug abuse, and had kept her with them. Her progress review reports “massive improvement”.

There had been early recognition that she was bright but easily distracted.

The focus and application needed to make use of this now began to emerge.

The teaching team had begun to build a picture of the wider issues that Alice was grappling with. Her mother also found it difficult to focus on her. With the lone care of another child with severe disabilities, Alice’s mother was also constantly distracted.

Called in to discuss her daughter’s issues with the teaching team, she brought the conversation round time and again to her other child. On the last occasion, Alice finished the meeting in floods of tears and clinging to a member of staff.

Beverley had also managed to keep on track against the odds. She travelled to college from across London, a choice that suggests a need to get away or at least make a fresh start.

At 16 she was entirely on her own. The address she gave to college was a hostel, but she no longer lived there. Hostel workers said she had moved out into non-supported housing. Friends said she slept wherever she could.

Certainly Beverley had no other address and collected her mail regularly from the hostel.

We do not know for sure what kind of family breakdown preceded her time in the hostel but there are reasons to suspect the worst.

Certainly, betrayal was always near the surface. A class role-play required a trusted friend to act outside the norms of friendship. Beverley found the experience unbearable and lost control of her response.

She could not talk about any of this to college staff. The guidance team was introduced at induction and brought back to work with the course group as a whole.

Beverley would not consider a one-to-one discussion. She derided the group sessions as a complete waste of time. Yet she could not keep away from the guidance unit and the team. She was always early for the sessions that they ran. She began to visit the unit at least once a week, usually to ask to use the phone.

She would not take structured help but she was always there. On one occasion, she instigated a major incident right outside the unit. On another, she was extremely offensive to the receptionist, which required a guidance officer and security to calm things down. She made sure to seek out the officer later in the day to apologise and explain. What would she have risked had she taken the step from the corridor or from reception into a counselling room?

Alice and Beverley have now gone, and we are left sad and wondering about the nature of those risks. We know the risks for the college if they had stayed: we would relinquish responsibility for the safety of our students and staff.

What would have been the risks for these learners? They had got through to term 3 and were in danger of completing their course. They had challenged the college on every level and were in danger of finding it able to bear what they doled out. They had, especially in Alice’s case, made changes to their behaviour and were in danger of becoming effective learners.

Of course this danger was never going to be realised. Students who cannot bear to stay and who cannot bring themselves to go will always be able to get us to make the choice for them. They will always be able to sabotage their re-engagement and prompt us to let them down once again.

The issue for colleges is the same as that for schools. The moral injunction not to exclude makes no sense where there is a real and continuing threat to the learning community.

We commit ourselves to deliver safe and stimulating learning opportunities.

Any failure to tackle threatening or deeply disruptive behaviour will have a knock-on effect on retention today and recruitment tomorrow.

The terms of engagement for students like Alice and Beverley have to fit the needs of the many thousands that study alongside them. But we also have to listen to the mixed messages sent by these young people who volunteer to turn up day after day to give us a hard time. College is possibly the only hope in their lives. We do not remove that lightly.

We must consider what it would take to make Alice and Beverley learning-ready, and how we could prepare them for a return to college which is safe for them and others. We are thinking about a new kind of learning model that might make sense for everyone involved.

It may need to be off-site; the worst incidents are mostly outside class.

It would need a different level of personal support and an even closer degree of curriculum integration. It would need clear boundaries rigorously upheld and a higher level of specialist staffing.

For some vulnerable young people, it might be a step too far. They might make the easy choice that Alice and Beverley never did and vote with their feet. But it might make the difference. As it is, Alice and Beverley are refused their appeal and we all fail.

Ruth Silver is principal of Lewisham College in south London