When FE Focus challenged Ruth Kelly - Education Secretary at the time - on the issue of criminal record checks and adult students, she appeared genuinely taken aback. It was as if the Government, in its pre-occupation with protecting children from staff, had missed the far more obvious threat from over-19s attending colleges.

Two years later, it is clear that the picture is just as unsatisfactory as it was then.

Sadly, the way events have unfolded at Doncaster College is an inevitable result of this oversight. It would be very easy to condemn the college for allowing someone with a record for downloading child pornography to study in a building where he is likely to come into contact with vulnerable teenagers - but it would be very wrong to do so.

First, bar-room criminology is not helpful in the discussion of such a sensitive matter. And it is clearly not within the expertise of educationists, or college managers, to decide whether such a conviction makes someone likely to be a physical threat.

Second, it is highly debatable whether excluding such people from education is beneficial to society at large, which has a wider interest in the rehabilitation of offenders, precisely because this makes them less of a danger.

So, in order to spare principals and college managers being forced into the position of having to act as the arbiter in these cases, a lead is needed from the Government on what kind of criminal convictions are acceptable among the adult students of colleges and how 14-19 students are to be protected.

Doncaster College’s case is not unique.

Far from being discredited, it simply stands out as a college that has taken action, where others may have chosen not to do so.

It is inevitable that colleges across the country have adult students whose criminal convictions, including offences involving physical harm, would bring in to question their suitability to be educated alongside teenagers. Clear regulations to tackle this issue should have been introduced long before the explosion in numbers of 14- to 16-year-olds in colleges in recent years, which has only served to make principals’ position on adult admissions even harder in respect of protecting their students.