Maybe summer schools for those who fail to attend, it will allow parents to work and hit the pupil with the loss of their summer holidays.

Though I suspect that these kids are not academic and so are really just wasting their time in an academic environment. If these kids are not academic, allow them to switch to vocational training from 14. IF they can spend the next few years learning a trade then their employment prospects will be so much better, and if they can leave with a trade they will actually be more motivated to attend.