The government proposes that only graduating students must pay back the cost of their fees in their plans to raise the cap on fees up to £9,000. Much may turn on what a "graduate" is. (The following explanation may amuse American and Canadian readers.) In North America, you either earn your bachelor degree or you do not: there are no alternative awards (am I wrong?). Thus, if you study for a B.A. in Philosophy or Political Science, then you either have earned this or you have not.
This is not true at many British universities. Students who might fail to earn sufficient credits for their "B.A. (Honours)" undergraduate degree may still qualify for other qualifications, including a "Pass Degree" or "Certificate of Higher Education" or even "Diploma of Attendance" depending upon how many credits have been passed. Thus, the idea of "the graduate" is perhaps more troublesome than one might think because if a "graduate" is someone who has earned a qualification then far more students may be affected: one need not complete all undergraduate credits to be considered a graduate.
However, if a "graduate" is only those who have earned a degree (and not merely a non-degree university qualification), then an interesting loophole arises. The loophole is this: students might fail to sit exams in their final year. Why? They would earn a qualification (perhaps "Certificate of Higher Education") without winning a degree - and, thus, they'd have a university qualification for free.
If the government wants to close this gap, then it probably should change the terms of agreement to say that students should pay back what the state has paid on their behalf. This would not permit students to get out of paying their debts by refusing to sit final exams, leaving university debt free and with a qualification (even if it is worth less than a full degree).
This is not to say that I endorse student fees: I do not. Nevertheless, this is yet another example of where this government appears to have ill thought its policies on higher education.